"simple earthen or glass cylindrical vessel," early 15c., possibly from rare Old French jarre "liquid measure smaller than a barrel," or more likely from Medieval Latin jarra (13c.) or Spanish or Catalan jarra (13c.), all ultimately from Arabic jarrah "earthen water vessel, ewer" (whence also Provençal jarra, Italian giarra), a general word in the 13c. Mediterranean sea-trade, which is from Persian jarrah "a jar, earthen water-vessel." Originally in English a large container used for importing olive oil.

In Britain in the 15th to 17th centuries, oil-lamps were overall not often used, because the oil was too expensive. Usage increased in the 17th century despite the expense. Olive oil was the most-often-used type of oil in the oil-lamps until the 18th century. The indications are good that no country or region exported more oil to Britain than southern Spain did in the 15th-17th centuries, with southern Italy coming second. ["English Words of Arabic Ancestry"]

1520s, "to make a brief, harsh, grating sound," often in reference to bird screeches; the word often is said to be echoic or imitative; compare jargon (n.), jay (n.), garrulous. Figurative sense of "have an unpleasant effect on" is from 1530s; that of "cause to vibrate or shake" is from 1560s. Related: Jarred; jarring. As a noun in this sense from 1540s.

"to spill carelessly" (transitive), 1550s, from slop (n.1). The intransitive sense of "be spilled or overflow" is from 1746. Related: Slopped; slopping.

c. 1400, "mudhole, puddle," probably from Old English -sloppe "dung" (in plant name cusloppe, literally "cow dung"), related to slyppe "slime" (from PIE root *sleubh- "to slide, slip").

The meaning "semi-liquid food" is by 1650s; that of "refuse liquid of any kind, household liquid waste" (usually slops) is from 1815. The meaning "affected or sentimental material" is by 1866.

late 14c., "loose outer garment" (early 14c. in a surname, sclopmongere), of obscure etymology, perhaps from Old English oferslop "surplice," which seems to be related to Middle Dutch slop, Old Norse sloppr (either of which also might be the source of the Middle English word), perhaps all from Proto-Germanic *slup-, from PIE root *sleubh- "to slide, slip" on the notion of a garment one "slips" on or into (compare sleeve).

The sense was extended generally to "clothing, ready-made clothing" (1660s), usually in plural slops, also a nickname for a tailor. Hence, also, slop-shop "shop where ready-made clothes are sold" (1723).

"bell-shaped glass jar," 1830, from bell (n.) + jar (n.). Especially one used by chemists. Earlier was bell-glass (1680s).

also jar-head, "U.S. Marine," by 1985 (but in a biographical book with a World War II setting), from jar + head (n.). Also used as a general term of insult (by 1979) and by 1922 as a Georgia dialectal word for "mule."

1727, "muddy, wet from slopping," from slop (n.1) + -y (2). By 1794 as "of a semi-liquid consistency." The meaning "loose, ill-fitting, slovenly" is recorded from 1825, influenced by slop (n.2). Related: Sloppily; sloppiness. Sloppy Joe was originally "loose-fitting sweater worn by girls" (1942); as a name for a kind of spiced hamburger, it is attested from 1961.

1814, "slush, sludge, a watery mess," probably a blend of slush and slop (n.1) in its Middle English sense of "muddy place." Later extended to weak, soggy food or writing.

of bottle or jar caps, 1959, from the verbal phrase; see twist (v.) + off (adv.).