We have already mentioned the verb assĭdēre formed with the prefix ad‑ ‘to, towards, at’, which originally meant ‘to sit by/beside’, which also came to mean ‘to sit beside and help in making judgments (as an assistant judge)’. The core of this word is the morpheme sĕd‑, which in this context is instantiated by its allomorph sĭd‑ (assĭdēre < ad+sĕd+ēre)
We saw that this verb is the source of sentar, since it is from a Vulgar Latin version of this verb, assedere, that the Spanish verb asentar(se) ‘to settle’ and, through it, sentar(se) ‘to sit’, is derived from, in particular, a new verb was created out of its present participle stem assedent‑, the first conjugation verb assedentare, source of asentar and, eventually, of sentar, by the loss of the intervocalic ‑d‑.
When we discussed the English word size in the previous section, we came across the Old French verb asseoir ‘to seat (= cause to sit)’ that was derived from Lat. assĭdēre. We said that the English noun size comes from Old French assise, presumably by mis-partition of the word (see previous section). We saw that the Old French noun assise was originally the past participle of the verb asseoir. The Old French verb is first attested in the 12th century and the noun assise derived from the verb’s past participle in the beginning of the 13th. There was another descendant of this same Old French assise in English, namely a doublet of Eng. size: the now historical noun assize [ə.ˈsaɪ̯z]. Its meaning was ‘a court which sat at intervals in each county of England and Wales to administer the civil and criminal law’ (COED).
English has a verb that ultimately comes from assĭdēre, namely the verb to assess [ə.ˈsɛs]. Eng. assess, first attested in the early 15th century, is a loanword from Old French assesser, which came from first conjugation, Medieval Latin assessare ‘to assess a tax; to fine’, which was originally a frequentative verb derived from assĭdēre’s passive participle stem assess‑ (as‑ses‑s‑us → as‑ses‑s‑are; for more on Latin frequentative verbs, see Chapter 8, §18.104.22.168). The meaning of this verb is derived ultimately from the ‘sitting beside as assistant judge’ sense of the verb assĭdēre. The main meaning of the English verb assess is to ‘evaluate or estimate the nature, value, or quality of’ and, derived from it, to ‘set the value of a tax, fine, etc., for (a person or property) at a specified level’ (COED).
The Old French verb assesser has not survived into Modern French. The only remnant of this verb is the derived noun assesseur, which, in legal terminology now means ‘magistrate's assistant’ (OHC). From this noun comes Eng. assessor [ə.ˈsɛ.səɹ], which entered the language in the late 14th century, being attested even before than the verb to assess. Its primary meaning today is ‘someone whose job is to calculate the value of something or the amount of tax someone should pay’ (COED), as in tax assessor or claims assessor.
The verb assess has no cognate in Spanish. It translates into this language as evaluar or estimar, cognates of the verbs evaluate and estimate, which are synonyms of Eng. assess. Spanish does have a noun and adjective asesor [a.se.ˈsoɾ] (fem. asesora), cognate of Eng. assessor, but it is a false friend. As a noun, Sp. asesor/a means ‘advisor, consultant’ and as an adjective, ‘advisory’, as in ingeniero asesor ‘consultant engineer’. The way Eng. assessor is rendered into Spanish is tasador in the context of taxes or insurance (derived from the verb tasar ‘to value, appraise’, a cognate of Eng. tax) and evaluador or perito in other situations.
From the noun asesor, Spanish has developed a few words: the verb asesorar ‘to advise’ and the its reflexive form asesorarse (con) ‘to get advise (from), get advised (by), consult (with)’, as well as the nouns asesoramiento ‘advice, advising’ and asesoría ‘consultancy; consultant’s office’.
Although Spanish has no cognate of Eng. assess, we must say that there is a rare Spanish verb asesar that is a false cognate (not a cognate). This verb is derived from the noun seso ‘brains, grey matter’ and, derived from it, ‘wisdom, prudence, discretion, sense, wit’, and its meaning is ‘to acquire good sense, brains, prudence, etc.’.
From the verb asses, English has derived the verb reassess by means of the Latinate suffix re‑ ‘back, again’. This verb translates into Spanish as volver a evaluar or reevaluar, volver a tasar or tasar de nuevo, as well as replantearse when referring to a situation or policy.
From the stem assĭd‑ of the verb assĭdēre, Latin formed the adjective assĭdŭus (fem. assĭdŭa) ‘constant, regular’ and ‘unremitting, incessant’ by means of the suffix ‑ŭ‑ that created first-second conjugation adjectives (masc. ‑ŭ-us, fem. ‑ŭ-a, neut. ŭ‑um). This suffix can be traced back to the Proto-Indo-European perfect active participle *‑wós (fem. *‑wéh₂). Both the English and Spanish reflexes of this adjective are learned ones. Sp. asiduo is first attested in the mid-15th century and Eng. assiduous in the 16th century. As in many other such Latin borrowings of adjectives in ‑ŭ-us, English added the ending ‑ous to the Latin word’s stem, an ending that is typically the reflex of the Latin first-second conjugation adjectival ending ‑ōs‑ (‑ōs‑us, ‑ōs‑a, ‑ōs‑um).
Unfortunately, Eng. assiduous and Sp. asiduo are not very good friends. Eng. assiduous means ‘showing great care and perseverance’ (COED) or ‘very careful to make sure that something is done properly or completely’ (DOCE) and translates into Spanish as diligente, aplicado, perseverante, or constante. Sp. asiduo also has the sense of perseverance but the main aspect of the meaning is constancy, continuity and, especially, frequency. Thus, although Sp. asiduo can sometimes be translated as assiduous, it is most commonly equivalent to Eng. regular, frequent, as in cliente asiduo ‘regular customer/client’, fumador asiduo ‘regular smoker’, or bebedor asiduo ‘frequent/heavy drinker’. Sp. asiduo can also be used as a noun as in un asiduo de la ópera ‘a regular operagoer’ or una asidua del cine ‘a regular movie-goer’.
Derived from these adjectives are the cognate nouns Eng. assiduity and Sp. asiduidad which are learned loanwords of Lat. assĭdŭĭtas or, more particularly, its accusative wordform assĭdŭĭtātem (ad‑sĭd‑ŭ‑ĭ‑tāt‑em). Its primary meaning was ‘a constant presence with any one (in order to serve, aid, etc.)’ (L&S). As in the case of the adjectives they are derived from, these nouns only partial friends. Eng. assiduity means ‘constant or close attention to what one is doing’ (COED) and thus, is best translated as aplicadamente, diligentemente, or even persistentemente (lit. ‘in an applied, diligent, or persistent manner’). Sp. asiduidad, which is more common than its English cognate, is a synonym of frecuencia ‘frequency’ and, thus, the best translation for this word is frequency. The noun asiduidad is often found in collocation with the preposition con ‘with’ to form the adverbial (prepositional) phrase con asiduidad ‘frequently’, a fancy synonym of the phrase con frecuencia (lit. ‘with frequency’). Note that in Latin the ‘constant presence’ sense of this word came to have an added connotation of ‘in order to serve’. This explains an earlier (now archaic or literary) sense of Eng. assiduity, namely ‘constant attentions to someone’.
Finally, English has also derived an adverb assiduously out of the adjective assiduous which is a synonym of diligently. It is first attested in the 17th century. It translates into Spanish as diligentemente, aplicadamente, con dedicación, or con perseverancia.
We finish this section by noting that all the words that we have seen here are derived from the Latin verb assĭdēre and none from the verb assīdĕre. It is very likely that by the time these two verbs made it into Romance, the second one of them had given in to the preponderance of the former. The idea of having two similar verbs of sitting seems to have been more than the descendants of the Romans cared to have to deal with, especially since the connection between them was not so clear.
 In Modern French, the word assise [a.ˈsiz] is still the past participle of the verb asseoir [a.ˈswaʀ]. It is also an adjective meaning ‘stable, established’ and ‘sitting (down)’, as well as a noun meaning ‘foundation, basis’, ‘stratum’, and, when speaking of a road, ‘bed’.
 Sp. evaluador is derived from the verb evaluar ‘to evaluate, assess’ and the noun perito/a ‘expert’ is a learned loanword from the Latin adjective perītus (fem. perīta) ‘skillful, skilled, expert, experienced, practised’, which shares a root with experto/a (Eng. expert) and experiencia (Eng. experience). Lat. perītus is primarily the passiveparticiple of the unattested verb *perior, from which Lat. experior ‘try, test, experience’ is derived. The noun perito/a is found in the terms perito/a agrónomo/a ‘agricultural technician’, perito/a industrial ‘engineer’ and perito/a mercantil ‘accountant’.
 The Spanish noun seso is a patrimonial word derived ultimately from Lat. sēnsus, passive participle of sĕntīre ‘to feel’, source of Sp. sentir ‘to feel’. In Latin, the participle sēnsus was converted into a noun that meant ‘perception, capability of feeling, ability to perceive’, as well as ‘feeling, sentiment’, and even ‘understanding, reason’. Thus, it is quite obvious that Sp. seso is a cognate of Eng. sense, a word that translates into Spanish as sentido, a noun derived by conversion from the (identical) newly regularized masculine past participle of the verb sentir.
 The word assĭdŭus was also sometimes used as a noun. In particular it was ‘a name given by Servius Tullius to the citizens of the upper and more wealthy classes, in opp. to proletarii, citizens of the lowest classes, who benefit the state only by their progeny (proles)’ (L&S).