From Middle English dream, dreem, dreeme, drem, dreme, dræm, from Old English drēam, drēm, drīm (“joy; melody, music; frenzy”), from Proto-West Germanic *draum, from Proto-Germanic *draumaz (“dream”), from earlier *draugmaz, from Proto-Indo-European *dʰrowgʰ-mos, from *dʰrewgʰ- (“to deceive”).

The sense of "dream", though not attested in Old English, may still have been present (compare Old Saxon drōm (“bustle, revelry, jubilation", also "dream”)), and was undoubtedly reinforced later in Middle English by Old Norse draumr (“dream”), from same Proto-Germanic root.

Cognates

Cognate with Scots dreme (“dream”), Saterland Frisian Droom (“dream”), West Frisian dream (“dream”), Dutch droom (“dream”), German Traum (“dream”), Limburgish Droum (“dream”), Luxembourgish Dram (“dream”), Yiddish טרוים (troym, “dream”), Danish and Norwegian Bokmål drøm (“dream”), Faroese dreymur (“dream”), Icelandic draumur (“dream”), Norwegian Nynorsk draum, drøm (“dream”), Swedish dröm (“dream”); also Breton drouk (“bad; evil”), Cornish drog (“bad; evil; invalid; nasty; wicked; wrong”), Irish droch- (“bad; ill-”), Manx drogh (“bad; evil”), Scottish Gaelic droch (“bad”), Welsh drwg (“bad; naughty”), Avestan 𐬛𐬭𐬎𐬲𐬀𐬌𐬙𐬌 (družaⁱti, “to deceive, mislead”), Bactrian λρωγο (lrōgo, “lie; falsehood”), Baluchi دروگ (darog, “lie; falsehood”), Central Kurdish درۆ (dro, “lie”), Northern Kurdish derew (“lie”), Pashto دروغ (droğ, “lie; falsehood”), Persian دُروغ (doruġ / durōġ, “lie; falsehood”), Sanskrit द्रुह्यति (druhyati, “to hurt; to bear malice or hatred; to be a foe or rival”).

The verb is from Middle English dreamen, dreme, dremen, dreomen, possibly (see below) from Old English drēman, drīeman, drȳman (“to rejoice; to play an instrument joyously; to sing a song joyfully”), from Proto-West Germanic *draumijan, from Proto-Germanic *draumijaną (“to be dream”), from the noun.

Cognates

Cognate with North Frisian drem, driime (“to dream”), Saterland Frisian drööme (“to dream”), West Frisian dreame, dreamje (“to dream”), Bavarian dramma, trama (“to dream”), Central Franconian drööme (“to dream”), Cimbrian truamen (“to dream”), Dutch dromen (“to dream”), German träumen (“to dream”), Low German draimen (“to dream”), Luxembourgish dreemen (“to dream”), Yiddish טרוימען (troymen, “to dream”), Danish and Norwegian Bokmål drømme (“to dream”), Faroese droyma (“to dream”), Icelandic dreyma (“to dream”), Norwegian Nynorsk drømma, drømme, drøyma, drøyme (“to dream”), Swedish drömma (“to dream, muse”).

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The derivation from Old English drēam is controversial, since the word itself is only attested in writing in its meaning of “joy, mirth, musical sound”. Possibly there was a separate word drēam meaning “images seen while sleeping”, which was avoided in literature due to potential confusion with the “joy” sense. Otherwise, the modern sense must have been borrowed from another Germanic language, most probably Old Norse. Since this is the common sense in all Germanic languages outside the British isles, a spontaneous development from “joy, mirth” to “dream” in Middle English is hardly conceivable. In Old Saxon, the cognate drōm did mean “dream”, but was a rare word.

Attested words for “sleeping vision” in Old English, both of which appeared in The Dream of the Rood, were mǣting (Middle English mæte, mete), from an unclear source, and swefn (Modern English sweven), from Proto-Germanic *swefnaz, from Proto-Indo-European *swepno-, *swep-; compare Ancient Greek ὕπνος (húpnos, “sleep”).