Etymology
1. O.E.
wæt "moist, liquid," from P.Gmc.
*wætaz (cf. O.Fris.
wet ). Also from the O.N. form,
vatr. All related to water. The verb is O.E.
wætan "to be wet."
Wet blanket "person who has a dispiriting effect" is recorded from 1879, from use of blankets drenched in water to smother fires (the phrase is attested in this literal sense from 1662).
All wet "in the wrong" is recorded from 1923, Amer.Eng.; earlier simply
wet "ineffectual," and perhaps ult. from slang meaning "drunken" (c.1700).
Wet-nurse is from 1620;
wet dream is from 1851;
wetback "illegal Mexican immigrant to the U.S." is attested from c.1924, from notion of wading the Rio Grande.
2. From Middle English wet (“wet, moistened”), wett, wette, past participle of Middle English weten (“to wet”), from Old English wǣtan (“to wet, moisten, water”), from Proto-West Germanic *wātijan, from Proto-Germanic *wētijaną (“to wet, make wet”), from Proto-Indo-European *wed- (“water, wet”) (also the source of water).
3. Cognate with Scots weit, wete (“to wet”), Saterland Frisian wäitje (“to wet; drench”), Icelandic væta (“to wet”). Compare also Middle English weet (“wet”), from Old English wǣt (“wet, moist, rainy”), from Proto-West Germanic *wāt, from Proto-Germanic *wētaz (“wet, moist”), related to Scots weit, weet, wat (“wet”), North Frisian wiat, weet, wäit (“wet”), Saterland Frisian wäit (“wet”), West Frisian wiet (“wet”), Middle Dutch wet (“wet, damp, watery”), Swedish and Norwegian våt (“wet”), Danish våd (“wet”), Faroese vátur (“wet”), Icelandic votur (“wet”). See: Proto-Germanic '
*wētijaną', Scots 'weit', Frisian, Saterlandic 'wäitje', Icelandic '
væta', Scots 'weit'.