put-on n.

Middle English putten, from late Old English *putian, "to thrust, push, shove" (someone or something; a sense now obsolete), also "to move or a thing physically so as to place it in some situation," implied in putung "instigation, an urging," literally "a putting;" related to pytan "put out, thrust out" (of eyes), probably from a Germanic stem that also produced Danish putte "to put," Swedish dialectal putta; Middle Dutch pote "scion, plant," Dutch poten "to plant," Old Norse pota "to poke."

Obsolete past tense form putted is attested 14c.-15c. From c. 1300 as "to hurl, cast, propel," especially "to throw with an upward and forward motion of the arm" (Will. Putstan is attested as a name from 1296). From mid-14c. in the figurative sense of "bring (someone) into some specified state or condition;" late 14c. as "subject (someone to something)," as in put to death, c. 1400; put to shame, mid-15c. From mid-14c. as "make a declaration, express in speech or writing," hence "express or state (in a particular way)," 1690s, also "propose or place before someone for consideration."

To put (something) back is from 1530s as "to hinder, delay;" 1816 as "restore to the original place or position." To put (something) down "end by force or authority" (a rebellion, etc.) is from mid-14c. To put upon (someone) "play a trick on, impose on" is from 1690s. To put up with "tolerate, accept, bear or suffer without protest or resentment" (1755) is perhaps from put up "to take up" (one's lodgings, etc.), 1727. To put (someone) up in the transitive sense of "lodge and entertain" is by 1766. To put (someone) on "deceive" is from 1958. To put upon (someone) "play a trick on, deceive, impose on" is from 1690s.

"in a position above and in contact with; in such a position as to be supported by;" also noting the goal to which some action is or has been directed; "about, concerning, regarding; in a position to cover;" as an adverb, "in or into a position in contact with and supported by the top or upper part of something; in or into place; in place for use or action; into movement or action; in operation," Old English on, unstressed variant of an "in, on, into," from Proto-Germanic *ana "on" (source also of Dutch aan, German an, Gothic ana "on, upon"), from PIE root *an- (1) "on" (source also of Avestan ana "on," Greek ana "on, upon," Latin an-, Old Church Slavonic na, Lithuanian nuo "down from").

Also used in Old English in many places where we now would use in. From 16c.-18c. (and still in northern England dialect) often reduced to o'. Phrase on to "aware" is from 1877.