shift (v.)
Old English sciftan, scyftan "arrange, place, order," also "divide, partition; distribute, allot, share," from Proto-Germanic *skiftan (cognates: Old Norse skipta "to divide, change, separate," Old Frisian skifta "to decide, determine, test," Dutch schiften "to divide, turn," German schichten "to classify," Schicht "shift"). This is said to be related to the source of Old English sceadan "divide, separate," (see shed (v.)).

c.1200 as "to dispose; make ready; set in order, control," also intransitive, "take care of oneself." From c.1300 as "to go, move, depart; move (someone or something), transport." Sense of "to alter, to change" appeared mid-13c. (compare shiftless). Meaning "change the gear setting of an engine" is from 1910; to shift gears in the figurative sense is from 1961. Related: Shifted; shifting.
shift (n.1)
c.1300, "a movement, a beginning," from shift (v.). This is the word in to make shift "make efforts" (mid-15c.). Sense of "change, alteration" is from 1560s. Sense of "means to an end" is from 1520s; hence "an expedient." Meaning "mechanism for changing gear in a motor vehicle" is recorded from 1914. Typewriter shift key is from 1893; shift-lock is from 1899.

Meaning "period of working time" (originally in a mine) is attested from 1809, with older sense "relay of horses" (1708); perhaps with sense influenced by a North Sea Germanic cognate word (such as North Frisian skeft "division, stratum," skaft "one of successive parties of workmen"). Similar double senses of "division" and "relay of workers" exist in Swedish skift, German schicht.
shift (n.2)
"body garment, underclothing," 1590s, originally used alike of men's and women's pieces, probably from shift (n.1), which was commonly used in reference to a change of clothes. In 17c., it began to be used as a euphemism for smock, and was itself displaced, for similar reasons of delicacy, in 19c. by chemise.