To bring things into harmony, or to make things compatible.
To provide parts to.
To provide the harmony for a melody.
To be in harmonious agreement.
To play or sing in harmony.
To contest, especially some trivial issue in a petty manner.
To complain or argue in a trivial or petty manner.
An objection or argument based on an ambiguity of wording or similar trivial circumstance; a minor complaint.