Other words derived ultimately from Lat. quătĕre
The Latin verb recŭtĕre was derived from Lat. quătĕre by means of the prefix re‑ ‘back, again’. Its meaning has been described as ‘to strike back or backwards’, ‘to cause to rebound’ (L&S), and/or ‘to strike so as to cause to vibrate’ (WLED). This verb has not been borrowed by English at any time, but it made it into Spanish as a patrimonial word, one that is rare but still in limited use today, namely recudir. This verb was quite common in Old Spanish had a number of meanings at the time, meanings that curiously are quite different from those of its Latin etymon, most of which are obsolete today. The verb is still found in major dictionaries, where most senses are marked as obsolete (ant.), such as ‘to reply’ (= replicar, responder in Modern Spanish) or ‘to go to a place’ (= acudir in Modern Spanish) (MM). The senses that are not marked obsolete should probably be marked as dialectal or archaic. The following are the two supposedly current senses of recudir in Spanish according to María Moliner’s dictionary: ‘return to the starting point’ and ‘to go and pay or give someone their due’ (MM).
Although clearly the verb recudir [re.ku.ˈðiɾ] is not a common one these days in Spanish, there is evidence that another Spanish verb, one that is much more common today than recudir, was created out of this verb, namely the verb acudir. Sp. acudir is first attested around the year 1330 and there is consensus among the scholars that this verb is nothing but a modification of an earlier recudir, created as a variant of it, by replacing the prefix re‑ ‘back, again’ with the prefix a‑ ‘to’. There is no Latin verb that acudir could have come from and the meanings of this verb are all the same that recudir used to have (DCECH). The reason for this change in prefix was presumably that the verb recudir had come to have meanings that did not agree with the prefix re‑ that typically meant ‘back’ or ‘again’. The verb recudir was very frequent in Spanish in the 12th and 13th centuries but then in the 14th century, when acudir was created, this verb began to replace recudir, until it become quite common by the early 15th century, coming close to replacing its source.
The verb acudir [a.ku.ˈðiɾ] does not have a simple translation into English. The DLE gives 11 senses for this word, but many are rare. Thus, in explaining this word’s meaning, we will follow the definitions in Diccionario de Uso del Español de América y España VOX, which gives us just three senses for this word, which can often be seen as synonyms of the verb ir ‘to go’:
1. ‘for a person to go somewhere either of one’s own accord or from a summons’, e.g. acudir a una cita ‘to go to/keep an appointment’
2. ‘for something to come someone, especially memories or mental images’, e.g. todos los recuerdos de su niñez acudieron a su mente ‘all her childhood memories went/rushed into his head’
3. ‘to resort to someone or something to get help in order to obtain some benefit’, e.g. acudir a un abogado ‘to go/resort to a lawyer’, acudir al diccionario ‘to go/turn to the dictionary’
As you can see, you can always translate acudir with the verb to go, so you can think of acudir as a fancy was of saying ‘to go’. However, in the first sense at least, one gets an additional sense of going somewhere because of a summons. All of these uses of acudir are somewhat literary or fancy in modern Spanish, however, though they are by no means rare and the word acudir can be said to be known to all native speakers of Spanish, unlike the word recudir, which is much rarer.
As to why Old Spanish recudir had acquired meanings that were so different from those of its Latin etymon recŭtĕre, which clashed with the meaning of the prefix re‑, it has been argued that this is due to a confusion of this verb in Romance times with the similar-sounding Latin verb recurrĕre ‘to run again/back’, a verb that Spanish has borrowed in recent times as recurrir. The passive participles also sounded very similar, recussus vs. recursus, which were also often confused. (Romance or Proto-Romance is the name given to the common language that descended from Vulgar Latin before it morphed into the different Romance languages, cf. Part I, Chapter 3.)[i] Thus, presumably the ancestor of recudir in Romance took on meanings from Romance recurrir, which were derived from those of Lat. recurrĕre.
As we mentioned, Modern Spanish has the verb recurrir, meaning ‘to appeal (something legally)’ and ‘to resort/turn (to someone)’. This Spanish verb is a relatively recent loanword from Latin, not a patrimonial word. It is a cognate of Eng. recur, a late 14th century loanword from Latin. Eng. recur means most basically ‘to occur again’, but when said of a thought or image, ‘to come back to one’s mind’, and used transitively (recur to) ‘to go back to in thought or speech’ (COED). As we can see, the cognates Eng. recur ~ Sp. recurrir are false friends. Eng. recur translates into Spanish as repetirse in most cases but also reproducirse such as when speaking of an illness, for example, whereas Sp. recurrir translates into English as to appeal to, to resort to, or to turn to. Incidentally, Lat. recurrĕre was derived by prefixation from the verb currĕre ‘to run, to move quickly’, the source of patrimonial Sp. correr, which also means ‘to run’ and ‘to move quickly’.
Although it is probably right that acudir was derived from recudir by replacement of the prefix, as the experts maintain, it is curious that Old Spanish speakers felt a need to replace the prefix re‑ of recudir by a‑ resulting in acudir. The reason is that there is no evidence for native speakers of Old Spanish that the initial element re‑ of recudir was a prefix at all. That is because the base ‑cudir is meaningless in Spanish since there is no verb *cudir in this language, just like it is unlikely that Modern English speakers associate the segment re‑ in the word retain with the prefix re‑ since there is no verb *tain in English. (In Spanish on the other hand, retener ‘to retain’ is clearly tied to the verb tener ‘to have, hold’, just like recorrer ‘to travel over, etc.’ is tied to correr ‘to run’.) This is a weakness in the argument that the re‑ was replaced by a‑ for the reason mentioned.
 The original says: ‘retroceder al punto de partida’ and ‘pagar o asistir a alguien con algo que le toca y debe percibir’ (MM).
 The original says: 1. ‘Ir [una persona] a un lugar por propia iniciativa o por haber sido llamado’; 2. ‘Presentarse [una cosa] a una persona, en especial recuerdos o imágenes mentales’; 3. ‘Recurrir a alguien o algo y valerse de su ayuda para conseguir un provecho’ (Vox).