A Grammatical Dictionary of Botanical Latin

unus, una, unum (irregular adj.A): one, a single, alone;

        singular                            plural [rarely used] 
      m.    f.   n.                    m.      f.     n. 
Nom. unus  una  unum                  uni     unae   una 
Gen.      unius                      unorum  unarum unorum 
Acc. unum  unam unum                  unos    unas   una 
Dat.      uni                                 unis 
Abl. uno  una   uno                           unis

NOTE: unus, una, unum represents the cardinal number ‘one.’

primus,-a,-um (adj.A), represents the ordinal number (numeral) ‘first.’

NOTE: una (adv.): at the same time, together, simultaneously; at the same place; see together;

- sporae una maturescentes, the spores maturing together.

NOTE: una (adv.) cum (prep. + abl.): along with, together with.

- [moss] calyptra cuculliformis, capsulae dimidiam partem tegens, una cum operculo decidua, laevis (DozyMoek), calyptra hooded, covering a half-part of the capsule, together with the operculum, deciduous, smooth.

NOTE: this adjective is almost universally used in the singular, but,

NOTE: the plural may be used with nouns considered to be only in the plural, such as (in ancient Rome) the agri decumates, lands on which tithes or land-taxes were paid (the decumates,-ium, relating to tithes), nouns known only in the plural, such as nuptiae,-arum (pl.f.I): marriage, nuptials; gemini,-orum (pl.m.II), twins; quadrijugi,-orum (pl.m.II): a team of four horses (Lewis & Short);

- in uno et eodemque individuo: in one and the same individual (see idem, eadem, idem (adj. & pronoun);

- [fungi] saepe in uno eodemque individuo hinc prorsus laevis, illinc confertius distantiusve minute et adpresse squamulosus (S&A), often in one and the same individual here [on one side] completely smooth, there [on the other] more densely or more distantly minutely and appressedly squamulose.

- uni gemini, individual twins; unae nuptiae, individual marriages, etc.

- tria Graecorum genera sunt, quorum uni sunt Athenienses (Cicero), there are three kinds of Greeks, some of whom are Athenians.

- species tamen plurimae adhuc imperfecte notae, flores unius alteriusve sexus v. fructus nobis desunt et difficile est divisiones revera naturales limitare (B&H), there are, however, many species at the present time imperfectly known, the flowers of one or the other sex or the fruits are absent with us and it is difficule to define divisions that are genuinely natural.

- unus de magistratibus, one of the magistrates.

- flores aut hermaphroditi aut sexus unius abortu monoici dioicive (DeCandolle), the flowers either hermaphrodite or by the abortion of one sex, monoicous or dioicous.

- flores in umbella saepius pauci, rarius ad unum reducti, flowers few more often in an umbel, more rarely reduced to one (sc. flower, s.m.III)).

- species ad 15, Africae australis incolae, cum una ex Africa tropica, species to 15, inhabitants of southern Africa, with one (sc. species) from tropical Africa.

- una e cotyledonibus in folium unicum plantae evolvitur, one of the cotyledons is developed in a single leaf of the plant ('una' is feminine as it modifies a fem. noun (cotyledon)).

- formae speciei unius polymorphae, forms of a single polymorphic species.

- species 2, una Tasmanica, 3 (vel unius varietates) Novo-Zelandicae, species 2, one Tasmanian, 3 (or varieties of one) of New Zealand (B&H).

- in unum 'into one, to one place, together.’

- species 2 quarum una per Archipelagum Malayanum dispersa, species 2, of which one is dispersed throughout the Malayan Archipelago.

- unus tantum, one alone (i.e. only).

- una sola per Americam australem late diffusa (B&H), only one throughout South America broadly distributed.

- cellularum divisio ad unam directionem, the division of the cells in [only] one direction.

NOTE: this is an irregular A adjective because the genitive sg. ends in -ius and the dative sg. in -i in all genders.

NOTE: Stearn (1983) indicated that the ordinal numerals “primus (the first), secundus (the second), tertius (the third), etc. are declined like unus ...”. Unfortunately this is not the case. All ordinal numbers are declined like regular A adjectives (gen.sg. -i (m.) -ae (f.), -i (n.), etc.).

NOTE: unus,-a,-um (irregular adj.A) may be used with ‘alter, altera, alterum’, q.v., ‘one’ (of two):

- species 2, una Altaica, altera Persica (B&H), species 2, one Altaic, the other Persian.

- folia pauca, unum post alteram provenientia, leaves few, one after the other growing out.

unus-quisque (m.), unaquaeque (f.), unumquidque (n.) = substantive (indefinite pronoun); a distributive pronoun.