dock (n.1) Look up dock at Dictionary.com
"ship's berth," late 15c., from Middle Dutch or Middle Low German docke, perhaps ultimately (via Late Latin *ductia "aqueduct") from Latin ducere "to lead" (see duke (n.)); or possibly from a Scandinavian word for "low ground" (compare Norwegian dokk "hollow, low ground"). Original sense perhaps "furrow a grounded vessel makes in a mud bank." As a verb from 1510s. Related: Docked; docking.
dock (n.2) Look up dock at Dictionary.com
"where accused stands in court," 1580s, originally rogue's slang, from Flemish dok "pen or cage for animals," origin unknown.
dock (v.) Look up dock at Dictionary.com
"cut an animal's tail," late 14c., from dok (n.) "fleshy part of an animal's tail" (mid-14c.), related to Old English -docca "muscle," from Proto-Germanic *dokko "something round, bundle" (cognates: Old Norse dokka "bundle, girl," Danish dukke "doll," German Docke "small column, bundle, doll, smart girl"). Meaning "to reduce (someone's) pay for some infraction" is first recorded 1822. Related: Docked; docking.
dock (n.3) Look up dock at Dictionary.com
name for various tall, coarse weeds, Old English docce, from Proto-Germanic *dokkon (cognates: Middle Dutch docke-, German Docken-, Old Danish dokka), akin to Middle High German tocke "bundle, tuft," and ultimately to the noun source of dock (v.).