Etymology
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nugatory (adj.)

"trifling, of no value; invalid, futile," c. 1600, from Latin nugatorius "worthless, trifling, futile," from nugator "jester, trifler, braggart," from nugatus, past participle of nugari "to trifle, jest, play the fool," from nugæ "jokes, jests, trifles," a word of unknown origin.

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nullify (v.)

"render legally null and void, render invalid," 1590s, from Late Latin nullificare "to esteem lightly, despise," literally "to make nothing," from Latin nullus "not any" (see null) + combining form of facere "to make" (from PIE root *dhe- "to set, put"). Related: Nullified; nullifying; nullifier.

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confute (v.)

"prove to be false or invalid, overthrow by evidence or stronger argument," 1520s, from French confuter, from Latin confutare "repress, check; disprove, restrain, silence," from assimilated form of com-, here perhaps an intensive prefix (see con-), + *futare "to beat," which is perhaps from PIE root *bhau- "to strike." Related: Confuted; confuting.

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fallacy (n.)
late 15c., "deception, false statement," from Latin fallacia "deception, deceit, trick, artifice," abstract noun from fallax (genitive fallacis) "deceptive," from fallere "deceive" (see fail (v.)). Specific sense in logic, "false syllogism, invalid argumentation," dates from 1550s. An earlier form was fallace (c. 1300), from Old French fallace.
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void (adj.)
c. 1300, "unoccupied, vacant," from Anglo-French and Old French voide, viude "empty, vast, wide, hollow, waste, uncultivated, fallow," as a noun, "opening, hole; loss," from Latin vocivos "unoccupied, vacant," related to vacare "be empty," from PIE *wak-, extended form of root *eue- "to leave, abandon, give out." Meaning "lacking or wanting" (something) is recorded from early 15c. Meaning "legally invalid, without legal efficacy" is attested from mid-15c.
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putative (adj.)

"supposed, reputed, commonly thought of or deemed," early 15c., from Late Latin putativus "supposed," from putat-, past-participle stem of Latin putare "to judge, suppose, believe, suspect," originally "to clean, trim, prune" (from PIE root *pau- (2) "to cut, strike, stamp"). At first especially in putative marriage, one which, though legally invalid due to an impediment, was contracted in good faith by at least one party. Related: Putatively.

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vain (adj.)
c. 1300, "devoid of real value, idle, unprofitable," from Old French vain, vein "worthless, void, invalid, feeble; conceited" (12c.), from Latin vanus "empty, void," figuratively "idle, fruitless," from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out."

Meaning "conceited, elated with a high opinion of oneself" first recorded 1690s in English; earlier "silly, idle, foolish" (late 14c.). Phrase in vain "to no effect" (c. 1300, after Latin in vanum) preserves the original sense. Related: Vainly; vainness. Compare also vainglory.
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pabulum (n.)

"food" for anything, "food" in its widest sense, "that which nourishes an animal or vegetable," 1670s, from Latin pabulum "fodder, food, nourishment," from PIE root *pa- "to feed" + instrumentive suffix *-dhlom. Related Pabular; pabulary; pabulous.

Pablum (1932), derived from this, is a trademark (Mead Johnson & Co.) for a soft, bland cereal used as a food for infants and weak and invalid persons, hence its figurative use (attested from 1970, first by U.S. Vice President Spiro Agnew) in reference to "mushy" political prose.

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crock (n.)

Middle English crokke, from Old English crocc, crocca "pot, earthen vessel, pitcher, or jar," from Proto-Germanic *krogu "pitcher, pot" (source also of Old Frisian krocha "pot," Old Saxon kruka, Middle Dutch cruke, Dutch kruik, Old High German kruog "pitcher," German Krug, Old Norse krukka "pot"). These all are perhaps from the same source as Middle Irish crocan "pot," Greek krossos "pitcher," Old Church Slavonic krugla "cup."

Specifically a receptacle for meal, butter, milk, etc., or in cooking; usually an earthen vessel but sometimes of brass or iron.

Used as an image of worthless rubbish since 19c., perhaps from the use of crockery as chamberpots. But there were other uses of crock, of uncertain relationship, such as "an old ewe" (1520s, Scottish), used contemptuously of debilitated or invalid persons (19c.). Also compare Middle English croke, crok "a hull, husk," figuratively "refuse," Low German krak "a thing of no value," colloquial English crock "soot, smut" (1650s).

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