From Bill Bryson's Dictionary of Troublesome Words 5 (Commonplace Book)

More geekery from Bill Bryson.

Languid, Limpid. Often confused. The first means limp or listless. The second means clear, calm, untroubled. [EDIT: I WROTE THIS BACKWARDS AT FIRST AND HAVE NOW FIXED IT.]

Libel, Slander. Although almost all dictionaries define libel as merely as a statement that defames another person or damages his reputation, it is worth remembering that it must do so unreasonably or inaccurately. It is the wrongness of a contention that makes it libelous, not the harshness or hostility of it. Libel must be published (usually written, but drawings can also constitute libel); libel comes from the Latin libellus, meaning "little book". Slander is used when remarks are merely spoken.

Like, As. This rule will cover you most of the time: as and as if are always followed by a verb (he played as if his life depended on it"); like never is ("He played like an expert").

Meticulous: correctly used, this word has a pejorative tone.

Minute detail: tautological.

Moribund: this word does not mean sluggish or troubled or struggling. It means dying. To be moribund is to be critically -- irreversibly -- ill.

Mutual exchange: tautological.