already (adv.)
c. 1300, "in a state of readiness" (an adjectival sense, now obsolete), literally "fully ready, quite prepared," a contraction of all + ready (adj.). Compare Norwegian, Danish allerede "already." As an adverb, "by this time, previous to some specified time," late 14c. Colloquial use in U.S. as a terminal emphatic (as in enough, already!) is attested from 1903, translating Yiddish shoyn, which is used in same sense. The pattern also is attested in Pennsylvania German and in South African.