Definition of as :
1. A Roman copper coin, originally of a pound weight ( 12 oz.); but reduced, after the first Punic war, to two ounces; in the second Punic war, to one ounce; and afterwards to half an ounce.
2. A Roman weight, answering to the libra or pound, equal to nearly eleven ounces Troy weight. It was divided into twelve ounces.
3. An ace.
4. Because; since; it being the case that.
5. Denoting equality or likeness in kind, degree, or manner; like; similar to; in the same manner with or in which; in accordance with; in proportion to; to the extent or degree in which or to which; equally; no less than; as, ye shall be as gods, knowing good and evil; you will reap as you sow; do as you are bidden.
6. Expressing a wish.
7. Expressing concession. ( Often approaching though in meaning).
8. For instance; by way of example; thus; - used to introduce illustrative phrases, sentences, or citations.
9. if; as though.
10. In the idea, character, or condition of, - limiting the view to certain attributes or relations; as, virtue considered as virtue; this actor will appear as Hamlet.
12. That, introducing or expressing a result or consequence, after the correlatives so and such.
13. While; during or at the same time that; when; as, he trembled as he spoke.
inasmuch as, evenly, equally, atomic number 33, arsenic, arsenous anhydride, since, arsenic trioxide, for, ratsbane, comparatively, American Samoa, white arsenic, arsenous oxide, being, Eastern Samoa, every bit, because
while (part of speech: adverb)