Monumental

wiktionary

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Borrowed from Late Latin monumentālis, from Latin monumentum; equivalent to monument +‎ -al.

etymonline

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monumental (adj.)

c. 1600, "pertaining to a monument," from Late Latin monumentalis "pertaining to a monument," from monumentum (see monument). From 1650s in the loose sense of "conspicuous, vast, stupendous, comparable to a monument." Extended sense of "historically prominent, conspicuous to posterity" is by 1844. Related: Monumentally.