available (adj.)youdaoicibaDictYouDict
mid-15c., "beneficial," also "valid, effective, capable of producing the desired effect," from avail + -able. Meaning "at one's disposal, capable of being made use of" is recorded from 1827.
efficacious (adj.)youdaoicibaDictYouDict
"sure to have the desired effect" (often of medicines), 1520s, from Latin efficaci-, stem of efficax "effectual, powerful" (see efficacy) + -ous. Related: Efficaciously; efficaciousness.
inefficacy (n.)youdaoicibaDictYouDict
"want of force or virtue to produce the desired effect," 1610s, from Late Latin inefficacia, from inefficacem (nominative inefficax), from in- "not, opposite of" (see in- (1)) + efficax (see efficacy).
inefficient (adj.)youdaoicibaDictYouDict
1750, "not producing the desired effect," from in- (1) "not, opposite of" + efficient. Related: Inefficiency (1749); inefficiently.
work (v.)youdaoicibaDictYouDict
a fusion of Old English wyrcan (past tense worhte, past participle geworht) "prepare, perform, do, make, construct, produce; strive after" (from Proto-Germanic *wurkijan); and Old English wircan (Mercian) "to operate, function, set in motion," a secondary verb formed relatively late from Proto-Germanic noun *werkan (see work (n.)). Sense of "perform physical labor" was in Old English, as was sense "ply one's trade" and "exert creative power, be a creator." Transitive sense "manipulate (physical substances) into a desired state or form" was in Old English. Meaning "have the expected or desired effect" is from late 14c. In Middle English also "perform sexually" (mid-13c.). Related: Worked (15c.); working. To work up "excite" is from c. 1600. To work over "beat up, thrash" is from 1927. To work against "attempt to subvert" is from late 14c.