英语词源字典 - 在线词源网站

availing (adj.)[availing 词源字典]: "advantageous," early 15c., present participle adjective from avail (v.).[availing etymology, availing origin, 英语词源]
failing (n.): late 14c., "failure;" 1580s, "defect, fault," verbal noun from fail (v.).
prevailing (adj.): 1590s, "vigorous;" 1680s, "widely accepted," present participle adjective from prevail (v.).
railing (n.): "construction in which rails form an important part," early 15c., verbal noun from rail (v.2). Technically, railings (late 15c.) are horizontal, palings are vertical.
retailing (n.): mid-14c., verbal noun from retail (v.).
sailing (n.): Old English seglinge, verbal noun from the source of sail (v.).
unavailing (adj.): "ineffectual, useless," 1660s, from un- (1) "not" + availing. Also see unavailable.
unfailing (adj.): late 14c., "never coming to an end, unceasing, everlasting, inexhaustible," from un- (1) "not" + present participle of fail (v.). Related: Unfailingly.