- antibiotics (1894) (Sp. antibióticos): noun/adjective formed in French (1889); the noun means ‘A substance which is capable of destroying or inhibiting the growth of bacteria or other micro-organisms; spec. one that is produced by another micro-organism (or is a synthetic analogue of a microbial product), and is used therapeutically’ (SOED). The word antibiotic was coined in French as antibiotique, derived from the Ancient Greek prefix ἀντι‑ (anti‑) ‘against’ and the adjective βιωτικός (biōtikós) ‘concerning or relating to life’, derived from the noun βίος (bíos) ‘life’.
- antivirals (1929?) (Sp. antivirales): noun/adjective derived from an earlier antivirus (1903) to refer to ‘a substance which is active or effective against viruses’ (OED) (the word antivirus is used to day mostly as a noun used in computing for ‘software designed to detect and usually delete computer viruses’ (WNTIU).
- antifungals (1945) or fungicides (Sp. fungicidas): antifungal is an adjective/noun, originally an adjective meaning ‘destroying fungi or inhibiting their growth’ (MWC); the noun fungicide was formed in English (1889) from fungus + ‑cide (fung‑i‑cide) (adj. fungicidal); Sp. fungicida (DRAE: 1970; cf. Part I, Chapter 5, §5.11.1)
- antiprotozoals (Sp. antiprotozoarios): a recently created noun/adjective (still not found in most dictionaries) for ‘a medicinal drug used to fight diseases (like malaria) that are caused by protozoa’ (WN); Spanish has calqued this word as antiprotozoarios.
- anthelmintics or antihelminthics (Sp. antihelmínticos): a late 17th century adjective for a medicine ‘used to destroy parasitic worms’ (COED), also used as a noun; it is a loanword from post-classical Latin anthelminthica (plural), used as noun of neuter plural of anthelminthicus or anthelminticus, a word formed from ant‑, a variant before h of the prefix ἀντι‑ (anti‑) ‘against’ and Ancient Greek ἕλμινθ-, combining form of ἕλμινς (hélmins; genitive: ἕλμινθος hélminthos) ‘intestinal, parasitic worm’ (Sp. lombriz intestinal, gusano parásito); Sp. antihelmíntico: RAE, 1884 and earlier dictionary: 1853)
The Spanish cognate miasma (RAE: 1817) is defined as ‘evil effluvium that was believed to be given off by diseased bodies, corrupt materials, or stagnant water’ (DLE, original: ‘Efluvio maligno que, según se creía, desprendían cuerpos enfermos, materias corruptas o aguas estancadas’). Sp. miasma was originally a masculine noun, just like all loanwords from Greek words derived with the noun-forming suffix ‑ma, such as problema, but it is not uncommon to hear even educated people use miasma as feminine today. This word does not have a figurative sense and it is used mostly in the plural, as miasmas.