Lacking ability: stupid foolish half-witted simple silly brainless daft dumb dim (the last four are predominantly colloquial words)
Clever, in a negative way, using brains to trick or deceive: cunning crafty sly
Attitudes towards life
Frank is pessimistic while Helen is optimistic – he always expects the worst to happen while she looks on the bright side.
It is strange that one of the twins is so extroverted while the other is so introverted – Ben loves being the focus of attention while Bill would far rather be alone with his thoughts.
I feel very tense (or wound-up/stressed-out) after a very busy day at work but, after a hot bath and a cup of tea, I`ll soon feel relaxed.
Jane is very sensible – she`d never do anything stupid. In other words, she`s very practical and down-to-earth.
Rupert is very sensitive – he gets very upset (or worked-up [more colloquial]), if he feels people are criticizing him.
Attitude towards other people
Enjoying other`s company: sociable gregarious
Disagreeing with others: quarrelsome argumentative
Taking pleasure in other`s pain: cruel sadistic
Relaxed in attitude to self and others: easy-going even-tempered laid-back
Not polite to others: impolite rude ill-mannered discourteous
Telling the truth to others: honest trustworthy reliable sincere
Unhappy if others have what one does not have oneself: jealous envious
One person`s meat is another person`s poison
Some characteristics can be either positive or negative depending on your point of view. The words in the right-hand column mean roughly the same as the words in the left-hand column except that they have negative rather than positive connotations.