Other forms: thought, thinking, thinks
To think is to use your mind — to form ideas, to hold an opinion, to consider something. It is among the twenty commonest verbs in English and it is irregular: think, thought, thought.
The two everyday jobs are worth separating. I think it will rain expresses an opinion, and there think is usually not continuous. I am thinking about moving describes mental activity in progress, and there it is. That is the classic state-versus-action split, and think is the verb it is usually taught with. Note the prepositions: think about a subject, think of an idea, think over a decision. And what do you think of it asks for an opinion, while what are you thinking about asks what is in your head.
1verbbelieveTo have an opinion or belief.
“I think she is right about the timing.”
2verbthinkTo use your mind to consider something.
“Think carefully before you answer.”
3verbrememberTo remember or call something to mind.
“I cannot think of her name.”
4verbintendTo intend or plan.
“We were thinking of leaving on Thursday.”
Too few real examples of this word to estimate which sense is commonest.
think is a mental act.
Old English thencan comes from a Proto-Indo-European root meaning to feel or perceive. Its close relative thyncan, meaning to seem, is a different verb entirely — it survives only in methinks, and the two fell together in Middle English, which is why thought serves as the past of both.
Middle English
thinken
English, today
think
From Middle English thinken. From Middle English thinken, thynken, thenken, thenchen, from Old English þenċan, from Proto-West Germanic þankijan, from Proto-Germanic þankijaną (“to think”), from Proto-Indo-European teng- (“to think, feel, know”). Cognate with Scots think, thynk (“to think”), frr teenk, taanke, tanke, tånke (“to think”), stq toanke (“to think”), West Frisian tinke (“to think”), Dutch denken, dinken (“to think”), Afrikaans dink (“to think”), Low German denken, dinken (“to think”), German denken (“to think”), Danish tænke (“to think”), Swedish tänka (“to think”), Norwegian Bokmål tenke (“to think”), Norwegian Nynorsk tenkja (“to think”), Icelandic þekkja (“to know, recognise, identify, perceive”), Gothic þagkjan (“to think”), Latin tongeō (“know”).
Etymology from Wiktionary, CC BY-SA