"small open vessel (smaller than aship) used to cross waters, propelled by oars, a sail, or (later) an engine," Middle Englishbot, from Old Englishbat, from Proto-Germanic*bait- (source also of Old Norsebatr, Dutchboot, GermanBoot), which is possibly from PIE root*bheid- "to split" (Watkins), if the notion is of making a boat by hollowing out a tree trunk or from split planking. Or it may be an extension of the name for some part of a ship.

Frenchbateau "boat" is from Old English or Norse. Spanishbatel, Italianbattello, Medieval Latinbatellus likewise probably are from Germanic languages. Of serving vessels resembling a boat, by 1680s (ship for "serving vessel or utensil shaped like a ship" is attested by 1520s). The image of beingin the same boat "subject to similar challenges and difficulties" is by 1580s; torock the boat "disturb stability" is from 1914.

"sequence of sensations or images passing through the mind of a sleeping person," mid-13c., probably related to Old Norsedraumr, Danishdrøm, Swedishdröm, Old Saxondrom "merriment, noise," Old Frisiandram "dream," Dutchdroom, Old High Germantroum, GermanTraum "dream." These all are perhaps from a Proto-Germanic*draugmas "deception, illusion, phantasm" (source also of Old Saxonbidriogan, Old High Germantriogan, Germantrügen "to deceive, delude," Old Norsedraugr "ghost, apparition"). Possible cognates outside Germanic are Sanskritdruh- "seek to harm, injure," Avestandruz- "lie, deceive."

Old Englishdream meant "joy, mirth, noisy merriment," also "music." Much study has failed to prove that Old Englishdream is the source of the modern word for "sleeping vision," despite being identical in form. Perhaps the meaning of the word changed dramatically, or "vision" was an unrecorded secondary Old English meaning ofdream, or there are two words here.

OED (1989) offers this theory for the absence ofdream in the modern sense in the record of Old English: "It seems as if the presence ofdream 'joy, mirth, music,' had causeddream 'dream' to be avoided, at least in literature, andswefn, lit. 'sleep,' to be substituted ...."

Thedream that meant "joy, mirth, music" faded out of use after early Middle English. According to Middle English Compendium, the replacement ofswefn (Middle Englishswevn) bydream in the sense "sleeping vision" occurs earliest and is most frequent in the East Midlands and the North of England, where Scandinavian influence was strongest.

Dream in the sense of "that which is presented to the mind by the imaginative faculty, though not in sleep" is from 1580s. The meaning "ideal or aspiration" is from 1931, from the earlier sense of "something of dream-like beauty or charm" (1888). The notion of "ideal" is behinddream girl (1850), etc.

Before it meant "sleeping vision" Old Englishswefn meant "sleep," as did a great many Indo-European "dream" nouns originally, such as Lithuaniansapnas, Old Church Slavonicsunu, and the Romanic words (Frenchsonge, Spanishsueño, Italiansogno all from Latinsomnium). All of these (including Old Englishswefn) are from PIE*swep-no-, which also is the source of Greekhypnos (from PIE root*swep- "to sleep"). Old English also hadmæting in the "sleeping vision" sense.

1560s, "full of dreams," hence "associated with dreams," fromdream (n.) +-y (2). Sense of "dream-like, vague, indistinct" is by 1848. Meaning "perfect, ideal," is noted as a teen vogue word in 1941, American English teen slang. Comparedreamboat "romantically desirable person;"dream girl, etc. Related:Dreamily; dreaminess.