online medical dictionary | definition of -a

<suffix>

<botany> A suffix used to form nouns from Greek, Latin, and Romanic feminine singular, especially for botanical or Latinized modern names of animals and plants (amoeba; campanula).

2. <chemistry> Oxides (alumina).

3. <geography> Geographical names (Africa).

4. Ancient or Latinized modern feminine names (Lydia; Hilda).

5. Forming plural nouns from Greek and Latin neuter plural, especially corresponding to a singular in -um or -on (addenda; phenomena), and in names (often from modern Latin) of zoological groups (Carnivora).

(06 Feb 2009)

<prefix>

A, as a prefix to English words, is derived from various sources.

1. It frequently signifies on or in, denoting a state, as in afoot, on foot, abed, amiss, asleep, aground, aloft, away, and analogically, ablaze, atremble, etc.

2. Implying motion onward or away, adding intensity to verbs of motion (arise, awake, avert, abridge).

3. Usually giving a force, and sometimes the sense of away, on, back, as in arise, abide, ago.

4. not, without (amoral, agnostic, apetalous, atheist, akin).

5. out, utterly (abash; affray).

Also a- before sc, sp, st, ac- before c, k, q, af- before f, ag- before g, al- before l, an- before n, ap- before p, ar- before r, as- before s, at- before t.

(05 Feb 2009)