1670s, "action of marking off of verse in metric feet," from Late Latin scansionem (nominative scansio) "a scanning," in classical Latin, "act of climbing," noun of action from past-participle stem of scandere "to climb" (see scan (v.)). There is a 1650s instance in English of the word in the literal sense of "action of climbing up."

in zoology and ornithology, "of or pertaining to climbing, used for climbing," by 1789, from Latin scansorius "used for climbing," from stem of scandere "to climb" (see scan (v.)).

1520s, "measured or prescribed size," altered (to conform to -ling words) from earlier scantlon, scantiloun, scantillon "dimension" (c. 1400), earlier a type of mason's rod for measuring thickness (c. 1300), a shortening of Old French escantillon (Modern French échantillon "sample pattern"), which is of uncertain origin; traditionally regarded as a deformed word ultimately from Latin scandere "to climb" (see scan (v.)). The sense has been influenced by scant (adj.). Meaning "small wooden beam" is by 1660s. Related: Scantlings.