Etymology
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immense (adj.)

"great beyond measure," early 15c., from Old French immense (mid-14c.), from Latin immensus "immeasurable, boundless," also used figuratively, from assimilated form of in- "not, opposite of" (see in- (1)) + mensus "measured," past participle of metiri "to measure" (from PIE root *me- (2) "to measure"). A vogue word in 18c., and mocked as such:

For instance, a long while every thing was immense great and immense little, immense handsome and immense ugly. Miss Tippet from the cloisters, could not drink tea with Master Parchment at the White Conduit-house, unless it was an immense fine day, yet probably it might rain so immense, there was no going without a coach. ["Town and Country Magazine" (in "Annual Register" for 1772)]
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immensity (n.)

mid-15c., immensite, "vastness; infinity," from Old French immensité (14c.) or directly from Latin immensitatem (nominative immensitas) "immeasurableness," noun of quality from immensus "immeasurable, boundless" (see immense). Immenseness is from c. 1600.

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*me- (2)
*mē-, Proto-Indo-European root meaning "to measure." Some words may belong instead to root *med- "to take appropriate measures."

It forms all or part of: amenorrhea; centimeter; commensurate; diameter; dimension; gematria; geometry; immense; isometric; meal (n.1) "food, time for eating;" measure; menarche; meniscus; menopause; menses; menstrual; menstruate; mensural; meter (n.1) "poetic measure;" meter (n.2) unit of length; meter (n.3) "device for measuring;" -meter; Metis; metric; metrical; metronome; -metry; Monday; month; moon; parameter; pentameter; perimeter; piecemeal; semester; symmetry; thermometer; trigonometry; trimester.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit mati "measures," matra "measure;" Avestan, Old Persian ma- "to measure;" Greek metron "measure," metra "lot, portion;" Latin metri "to measure."
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brobdingnagian (adj.)
"huge, immense, gigantic," 1728, from Brobdingnag + -ian.
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ettin (n.)

an old word for "a giant," extinct since 16c., from Old English eoten "giant, monster," from Proto-Germanic *itunoz "giant" (source also of Old Norse iotunn, Danish jætte), perhaps "immense eater," or "man-eater," from suffixed form of PIE root *ed- "to eat."

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scads (n.)

"large amounts," 1869, American English, earlier "a dollar" (1855, usually in plural), a word of uncertain origin. Unknown connection to scad, the fish, which, along the British coasts, were often very abundant and occasionally seen in immense shoals.

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astronomical (adj.)
1550s, "pertaining to astronomy," from astronomy + -ical. Popular meaning "immense, concerning very large figures" (as sizes and distances in astronomy) is attested from 1899. Astronomical unit (abbreviation A.U.) "mean distance from the Earth to the Sun," used as a unit of measure of distance in space, is from 1909. Related: Astronomically.
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tremendous (adj.)
1630s, "awful, dreadful, terrible," from Latin tremendus "fearful, to be dreaded, terrible," literally "to be trembled at," gerundive form of tremere "to tremble" (see tremble (v.)). Hyperbolic or intensive sense of "extraordinarily great or good, immense" is attested from 1812, paralleling semantic changes in terrific, terrible, dreadful, awful, etc. Related: Tremendously.
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exiguous (adj.)
"scanty, small, diminutive," 1650s, from Latin exiguus "small, short; petty, paltry, poor, mean; scanty in measure or number; strict," literally "measured, exact," from exigere "to drive out, take out," also "to finish, measure," from ex "out" (see ex-) + agere "to set in motion, drive, drive forward; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move"). Compare immense "huge," literally "unmeasured."
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