Meaning of A- in English

A-

~ 1

(often an- before a vowel)

■ prefix not; without: atheistic.

Origin

from Gk.

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~ 2

■ prefix

1》 to; towards: aside.

2》 in the process of: ~hunting.

↘in a specified state: aflutter.

Origin

OE, unstressed form of on .

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~ 3

■ prefix variant spelling of ad- before sc , sp , and st (as in ascend , aspire and astringent ).

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~ 4

■ prefix

1》 of: anew.

2》 utterly: abash.

Origin

unstressed form of of (sense 1); Anglo-Norman Fr. ~ , from L. ex (sense 2).

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.