Answer:

vainest

Answer	Crossword Clue
VAINEST	Most futile
VAINEST	Most conceited
VAINEST	Least humble

VAINEST	Least significant
VAINEST	Least modest
VAINEST	Least modest.
VAINEST	Most conceited.
VAINEST	Most peacockish
VAINEST	Most likely to stop at a mirror
VAINEST	Most apt to preen
VAINEST	Most excessively proud

VAINEST	Most likely to stop at mirrors
VAINEST	Most prone to preening