Origin and history of widdershins

Middle English senden, from Old English sendan "dispatch (as a messenger, on an errand); order or cause to go or pass (from one place to another);" also "send forth, emit; throw, propel, cause to be delivered or conveyed."

This is reconstructed to be from Proto-Germanic *sond- "make to go" (source also of Old Saxon sendian, Old Norse senda, Old Frisian senda, Middle Low German and Middle Dutch senden, Dutch zenden, German senden, Gothic sandjan), causative form of *sinþan "to go, journey" (source of Old English sið "way, journey," Old Norse sinn, Gothic sinþs "going, walk, time"). This in turn is from the PIE root *sent- "to head for, go" (source also of Lithuanian siųsti "send"), for which see sense (n.). For the linguistic connection of "go" and "sense," compare German sinnen (past tense sann) "go over in the mind, review, reflect upon." 

The meaning cause (someone) to go into some specified state (send to sleep, etc.) is by 1831. The slang sense of "to transport with emotion, delight" is by 1932, in American English jazz slang. To send word "transmit or dispatch a message" (to someone) is from c. 1200. To send for "summon, send a message or messenger for" is by late 14c.

originally noting opposition, competition, entanglement, but in Middle English shifting to note association or connection; proximity, harmony, alliance.

It is from Old English wið "against, opposite, from;" also "toward, by, near." The sense shifted in Middle English to denote association, combination, and union, partly by influence of Old Norse cognate viðr "against," but also "toward, at," and also perhaps by association with Latin cum "with" (as in pugnare cum "fight with"). Also compare obsolete wine "friend," related to win "to strive, struggle, fight" (see win (v.)) probably on the notion of "comrade-in-arms."

In this sense denoting company or connection it replaced Old English mid, which survives as a prefix (as in midwife; see mid (prep.)). The original sense of "against, in opposition" is retained in compounds such as withhold, withdraw, withstand.

The Old English word is a shortened form related to the first element in widdershins, from Proto-Germanic *withro- "against" (source also of Old Saxon withar "against," Middle Dutch, Dutch weder, Dutch weer "again," Gothic wiþra "against, opposite").

This is reconstructed to be from PIE *wi-tero-, literally "more apart," suffixed form of *wi- "separation" (source also of Sanskrit vi "apart," Avestan vi- "asunder," Sanskrit vitaram "further, farther," Old Church Slavonic vutoru "other, second"). Compare widow (n.).

Phrase with child "pregnant" is recorded from c. 1200. With it "cool, hip, up-to-date" is recorded by 1931 in Black English. What's with? "what are the circumstances of or explanation for" is by 1940.

With and by are so closely allied in many of their uses that it is impossible to lay down a rule by which these uses may at all times be distinguished. The same may be said, but to a less extent, of with and through. [Century Dictionary, 1891]

French avec "with" was originally avoc, from Vulgar Latin *abhoc, from apud hoc, literally "with this."