c. 1300, "a movement, a beginning," from shift (v.); by mid-15c. as "an attempt, expedient, or means." This is the word in make shift "make efforts" (mid-15c.; see makeshift). The specific sense of "means to an end" is from 1520s, hence "a device, a trick." The sense of "change, alteration" in character, place, position, etc., is from 1560s.
The meaning "mechanism for changing gear in a motor vehicle" is recorded from 1914. Typewriter shift key is so called by 1893; its shift-lock is so called from 1899.
The meaning "period of working time" (originally in a mine) is attested from 1809, perhaps from or influenced by an older sense "relay of horses" (1708); perhaps also 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" is in Swedish skift, German schicht.
"body garment, underclothing," 1590s, originally used alike of men's and women's garments, probably from shift (n.1), which was commonly used in reference to a change of clothes. In 17c., shift (n.) in this sense began to be used as a euphemism for smock, and was itself displaced, for similar reasons of delicacy, in 19c. by chemise.
Middle English shiften, from Old English sciftan, scyftan "arrange, place, put in order" (a sense now obsolete), also "divide, separate, partition; distribute, allot, share" (now obsolete or provincial), from Proto-Germanic *skiftan (source also of 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.)).
By c. 1200 as "to dispose; make ready; set in order, control," also intransitive, "take care of oneself." Thus "manage to succeed, make out a livelihood" (as in shift for oneself, 1510s; also compare makeshift).
The sense of "to alter, to change" appeared by mid-13c. (compare shiftless). Also from mid-13c. in the transitive sense of "remove and replace with another or others," originally especially of clothing, hence "put on and replace one's clothes" (c.1400).
From c. 1300 as "to go, move, depart; move (someone or something), transport" as from one place or position to another. The meaning "change the gear setting of an engine" is from 1910; to shift gears in the figurative sense is from 1961. Related: Shifted; shifting.
1580s (transitive and intransitive), not found in Middle English, probably from a Low German source such as Middle Dutch splitten, from Proto-Germanic *spleitanan (source also of Danish and Frisian splitte, Old Frisian splita, German spleißen "to split"), from PIE *(s)plei- "to split, splice" (see flint).
U.S. slang meaning "leave, depart" first recorded 1954. Of couples, "to separate, to divorce" from 1942. To split the difference is suggested from 1715; to split (one's) ticket in the U.S. political sense is attested from 1842. To split hairs "make too-nice distinctions" is from 1670s (split a hair; the figurative image itself is implied in Shakespeare). Splitting image "exact likeness" is from 1880. To split the atom is from 1909.
1590s, "narrow cleft, crack, fissure," from split (v.). Meaning "piece of wood formed by splitting" is from 1610s. Meaning "an act of separation, a divorce" is from 1729. From 1861 as the name of the acrobatic feat. Meaning "a drink composed of two liquors" is from 1882; that of "sweet dish of sliced fruit with ice cream" is attested from 1920, American English. Slang meaning "share of the take" is from 1889. Meaning "a draw in a double-header" is from 1920.
1640s, past-participle adjective from split (v.). Split decision is from 1946 of court rulings, 1951 in boxing. Split shift is from 1904. Split personality first attested 1899.