Able-bodied (can be a character trait - he/she is able-bodied as opposed to disabled.
Abrasive (can be used to describe someone who is abrupt/rude)
Abrupt (character trait)
Absent (can be absent minded but physically absent)
Absolutist (character trait)
Abstemious (indulging only very moderately in something, especially food and drink.)
Abstracted (lacking concentration on what is happening around one.) not common.
Abusive (character trait)
Academic (He/She is an academic - teacher or researcher?)
Accepting (can be a character trait)
Accessible (not really a character trait.)
Accident-prone (yes, character trait)
Accommodating (can be - also known as a 'pushover')
Accomplished (can be a character trait)
Accurate (character trait)
Accusing (not really unless that's their basic nature)
Acerbic (especially of a comment or style of speaking) sharp and forthright.
Acquiescent (ready to accept something without protest, or to do what someone else wants.)
Acquisitive (excessively interested in acquiring money or material things. Not a trait)
adamant (someone who stands up for what they believe in) Not a trait really.
adaptable (someone who is flexible - can be a character trait)
addictive (not a trait though someone can have an addictive personality)
adolescent (It's about the age of the person, not a trait as such)
adorable (someone's opinion of a person) not really a trait.
adrift (can say someone is adrift but not really a trait)
adroit (means someone who is good at something) Not a trait.
adventurous (can be part of the person's makeup, could be a trait)
affable (someone who is kind and nice - could be classed as a trait)
affected (not really, someone is affected by an outside source, not a trait)
affectionate (character trait)
aficionado (a person who is very knowledgeable and enthusiastic about an activity, subject, or pastime.- not really a trait)