think

To ponder, to go over in one's mind.

Idly, the detective thought what his next move should be.

Had we but world enough and time / This coyness, lady, were no crime. / We would sit down, and think which way / To walk, and pass our long love's day.

To have (some statement) in one's mind; to say to oneself mentally.

"I should phone my mother," I thought.

So this was my future home, I thought! Certainly it made a brave picture. I had seen similar ones fired-in on many a Heidelberg stein. Backed by towering hills,[…]a sky of palest Gobelin flecked with fat, fleecy little clouds, it in truth looked a dear little city; the city of one's dreams.

To communicate to oneself in one's mind, to try to find a solution to a problem.

I thought for three hours about the problem and still couldn’t find the solution.

Thinks I to myself, “Sol, you're run off your course again. This is a rich man's summer ‘cottage’ and if you don't look out there's likely to be some nice, lively dog taking an interest in your underpinning.”

To conceive of something or someone

I tend to think of her as rather ugly.

Think of banking today and the image is of grey-suited men in towering skyscrapers. Its future, however, is being shaped in converted warehouses and funky offices in San Francisco, New York and London, where bright young things in jeans and T-shirts huddle around laptops, sipping lattes or munching on free food.

To be of opinion (that); to consider, judge, regard, or look upon (something) as.

I don't think it worth complaining about the leak in the roof, is it?

I hope you won’t think me stupid if I ask you what that means.

An act of thinking; consideration (of something).

I'll have a think about that and let you know.

To seem, to appear.

And whanne syr launcelot sawe he myghte not ryde vp in to the montayne he there alyghte vnder an Appel tree […] And then he leid hym doune to slepe And thenne hym thoughte there came an old man afore hym the whiche sayd A launcelot of euylle feythe and poure byleue wherfor is thy wille tourned soo lyghtely toward thy dedely synne