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]
(..) We need fresh towels in . Don't ask why, just do it. You have the flight number. He leaves tomorrow out of JFK. He'll be easy to spot. He's got white hair, a thin mustache... ...brimming with self-confidence and completely lost. - Did you get the stuff? - Yes. Good. (..)2006 The Pink Panther