duck
One option is baby.
a four letter word beginning with X is xebec (a small historical three masted sailing ship with square sails.
Envy Is A 4-Letter Word
tiny. that's the only one i can think of..
teal
teal
Duck
duck
teal
Duckling is the English word for a baby duck.
duck
teal
The smaller 4 letter word could be "Tiny".
gnat
lyre
a Bump?