Etymology
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worm (n.)

Old English wurm, variant of wyrm "serpent, snake, dragon, reptile," also in later Old English "earthworm," from Proto-Germanic *wurmiz (source also of Old Saxon, Old High German, German wurm, Old Frisian and Dutch worm, Old Norse ormr, Gothic waurms "serpent, worm"), from PIE *wrmi- "worm" (source also of Greek rhomos, Latin vermis "worm," Old Russian vermie "insects," Lithuanian varmas "insect, gnat"), from PIE *wrmi- "worm," from root *wer- (2) "to turn, bend."

The ancient category of these was much more extensive than the modern, scientific, one and included serpents, scorpions, maggots, and the supposed causes of certain diseases. For substitution of -o- for -u-, see come. As an insult meaning "abject, miserable person" it dates from Old English. Worms "any disease arising from the presence of parasitic worms" is from late Old English. Can of worms figurative for "difficult problem" is from 1951, from the literal can of worms a fisherman might bring with him, on the image of something all tangled up.

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worm (v.)
"to move like a worm," c. 1600, from worm (n.). In figurative senses attested from 1620s, suggesting patient, sinuous progress. Meaning "to free from worms" is from 1620s. Related: Wormed; worming.
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meal-worm (n.)

"grub or larva of a meal-beetle," infesting granaries, etc., 1650s, from meal (n.2) + worm (n.).

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maw-worm (n.)

"an intestinal worm infesting the stomach," c. 1600, from maw (n.) + worm (n.).

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glow-worm (n.)
early 14c., from glow (v.) + worm (n.). Actually the wingless female form of a beetle (Lampyris noctiluca). The males have wings but do not glow.
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ear-worm (n.)
1880, "boll-worm, corn parasite" (corn-ear-worm attested from 1855), from ear (n.2) + worm (n.). Also an old alternative name for "earwig" (from ear (n.1)); from 1881 as "secret counselor." From 1989 as "annoyingly unforgettable pop song or part of a song."
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silkworm (n.)
Old English seolcwyrm; see silk + worm (n.).
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tapeworm (n.)
1705, from tape (n.) + worm (n.); so called for its ribbon-like shape.
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pinworm (n.)

also pin-worm, "small, thread-like worm," by 1837, from pin (n.) + worm (n.).

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wormhole (n.)
also worm-hole, 1590s, "hole made by a burrowing insect" (in fruit, timber, etc.), from worm (n.) + hole (n.). Astrophysics sense is attested from 1957.
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