Entries related to set-to
Old English settan (transitive) "cause to sit, put in some place, fix firmly; build, found; appoint, assign," from Proto-Germanic *(bi)satejanan "to cause to sit, set" (source also of Old Norse setja, Swedish sätta, Old Saxon settian, Old Frisian setta, Dutch zetten, German setzen, Gothic satjan), causative form of PIE *sod-, a variant of root *sed- (1) "to sit." Also see set (n.2).
The intransitive sense from c. 1200, "be seated." The word was used in many disparate senses by Middle English; sense of "make or cause to do, act, or be; start" and that of "mount a gemstone" attested by mid-13c. Confused with sit since early 14c. Of the sun, moon, etc., "to go down," recorded from c. 1300, perhaps from similar use of the cognates in Scandinavian languages. To set (something) on "incite to attack" (c. 1300) originally was in reference to hounds and game.
Old English to "in the direction of, for the purpose of, furthermore," from West Germanic *to (source also of Old Saxon and Old Frisian to, Dutch toe, Old High German zuo, German zu "to"), from PIE pronominal base *do- "to, toward, upward" (source also of Latin donec "as long as," Old Church Slavonic do "as far as, to," Greek suffix -de "to, toward," Old Irish do, Lithuanian da-), from demonstrative *de-. Not found in Scandinavian, where the equivalent of till (prep.) is used.
The nearly universal use of to with infinitives (to sleep, to dream, etc.) arose in Middle English out of the Old English dative use of to, and it helped drive out the Old English inflectional endings (though in this use to itself is a mere sign, without meaning).
Commonly used as a prefix in Middle English (to-hear "listen to," etc.), but few of these survive (to-do, together, and time references such as today, tonight, tomorrow — Chaucer also has to-yeere). To and fro "side to side" is attested from mid-14c. Phrase what's it to you "how does that concern you?" (1819) is a modern form of an old question:
Huæd is ðec ðæs?
[John xxi:22, in Lindisfarne Gospel, c.950]