avail (v.) Look up avail at Dictionary.com
c. 1300, availen, "to help (someone), assist; benefit, be profitable to; be for the advantage of; have force or efficacy, serve for a purpose," apparently an Anglo-French compound of Old French a- "to" (see ad-) + vaill-, present stem of valoir "be worth," from Latin valere "be strong, be worth" (see valiant). Related: Availed; availing. As a noun, from c. 1400.