From WordNet (r) 3.0 (2006) [wn]:
afraid
adj 1: filled with fear or apprehension; "afraid even to turn
his head"; "suddenly looked afraid"; "afraid for his
life"; "afraid of snakes"; "afraid to ask questions"
[ant: fearless, {unafraid(p)}]
2: filled with regret or concern; used often to soften an
unpleasant statement; "I'm afraid I won't be able to come";
"he was afraid he would have to let her go"; "I'm afraid
you're wrong"
3: feeling worry or concern or insecurity; "She was afraid that
I might be embarrassed"; "terribly afraid of offending
someone"; "I am afraid we have witnessed only the first phase
of the conflict"
4: having feelings of aversion or unwillingness; "afraid of hard
work"; "afraid to show emotion"
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Afraid \A*fraid"\, p. a. [OE. afrayed, affraide, p. p. of
afraien to affray. See Affray, and cf. Afeard.]
Impressed with fear or apprehension; in fear; apprehensive.
[Afraid comes after the noun it limits.] "Back they recoiled,
afraid." --Milton.
[1913 Webster]
Note: This word expresses a less degree of fear than
terrified or frightened. It is followed by of before
the object of fear, or by the infinitive, or by a
dependent clause; as, to be afraid of death. "I am
afraid to die." "I am afraid he will chastise me." "Be
not afraid that I your hand should take." --Shak. I am
afraid is sometimes used colloquially to soften a
statement; as, I am afraid I can not help you in this
matter.
[1913 Webster]
Syn: Fearful; timid; timorous; alarmed; anxious.
[1913 Webster]