Feeling uncertain about something
DOUBTFUL
A sum of money that is owed or due
DEBT
The short, thick first digit of the human hand, set lower and apart from the other four and opposable to them
THUMB
A person or animal that climbs
CLIMBER
Give one's attention to a sound
LISTEN
Making use of clever and indirect methods to achieve something
SUBTLE
Past and past participle of catch.
CAUGHT
A medium-sized sailing boat equipped for cruising or racing
YACHT
Relating to the sense of hearing:
AUDITORY
The assembled spectators or listeners at a public event such as a play, film, concert, or meeting
AUDIENCE