He plans to 'thin' (out) the young carrots in the garden. [=to remove some of them so that there is more room between the remaining carrots]
His hair is a little 'thin' on top. = He's a little 'thin' on top. [=he does not have a lot of hair on the top of his head]
The bank's decision to raise rates could be 'the thin end of the wedge'. [=many other banks may also decide to raise rates]
(..) - That's not the knife, remember? - Oh, brilliant! - I'm tellin' you, this is the craziest. I mean, what are we supposed to believe? You're pullin' stories out of thin air. A guy like this, if he's sittin' ringside at the Dempsey-Firpo fight, he'd be trying to tell you that... (..)1957 12 Angry Men