Other forms: tomorrows
Tomorrow is the day after today. Say it on a Monday and you mean Tuesday: 'See you tomorrow,' called from the doorway as someone pulls their coat on.
Tomorrow takes no preposition — you say tomorrow morning, tomorrow night, tomorrow at six, never 'in tomorrow'. It is a noun as well as an adverb: tomorrow is my birthday, tomorrow's weather, the day after tomorrow. Stretched out, tomorrow means the future in general — the world of tomorrow, tomorrow's children. There is a whole family of small phrases about putting things off, and 'tomorrow never comes' is the sharpest of them. Do not confuse it with 'the next day', which you use when telling a story set in the past.
1adverbtomorrowOn the day after today.
“I'll call you tomorrow when the shop opens.”
2noundayThe day after today.
“Tomorrow is the last day to send the form back.”
3nounfutureThe future.
“The exhibition imagines the cities of tomorrow.”
Too few real examples of this word to estimate which sense is commonest.
Tomorrow was two words before it was one. Old English said tō morgne, 'at morning', which is to plus morrow, and the morgen inside it goes back to Proto-Germanic murganaz, 'morning', perhaps from a Proto-Indo-European root mergʰ-, 'to blink, to twinkle'. German and Dutch still use morgen for both the morning and the day after this one.
Proto-Indo-European
*mergʰ- — to blink, to twinkle
Proto-Germanic
*murganaz — morning
Old English
tō morgne — tomorrow
Middle English
tomorwe
English, today
tomorrow
Built from
From Middle English tomorwe, tomorwen, from Old English tō morgne (“tomorrow”), from tō (“at, on”) + morgen (dative of morgen (“morning”)), from Proto-Germanic murganaz (“morning”), perhaps from Proto-Indo-European mergʰ- (“to blink, to twinkle”), equivalent to to + morrow. Compare French demain, Dutch morgen, German morgen, Swedish imorgon or Danish i morgen.
Etymology from Wiktionary, CC BY-SA