A-. A, as a prefix to English words, is derived from various sources. (1) It frequently signifies on or in (from an, a forms of AS. on), denoting a state, as in afoot, on foot, abed, amiss, asleep, aground, aloft, away (AS. onweg), and analogically, ablaze, atremble, etc. (2) AS. of off, from, as in adown (AS. ofdune off the dun or hill). (3) AS. a- (Goth. us-, ur-, Ger. er-), usually giving an intensive force, and sometimes the sense of away, on, back, as in arise, abide, ago. (4) Old English y- or i- (corrupted from the AS. inseparable particle ge-, cognate with OHG. ga-, gi-, Goth. ga-), which, as a prefix, made no essential addition to the meaning, as in aware. (5) French à (L. ad to), as in abase, achieve. (6) L. a, ab, abs, from, as in avert. (7) Greek insep. prefix α without, or privative, not, as in abyss, atheist; akin to E. un-. Besides these, there are other sources from which the prefix a takes its origin.

A-mornings
A-morn´ings, adv. [See Amorwe. The -s is a genitival ending. See -wards.] In the morning; every morning. [Obs.]
"And have such pleasant walks into the woods A-mornings." - J. Fletcher.

A-sea, adv. [Pref. a- + sea.] On the sea; at sea; toward the sea.

A-tiptoe
A-tip´toe, adv. On tiptoe; eagerly expecting.
"We all feel a-tiptoe with hope and confidence." - F. Harrison.