A side report or statement.

An indirect or concealed purpose or design.

A retired place, spot, or situation; somewhere out-of-the-way.

(dated) A leisure hour.

A notebook or memorandum book. / A subordinate book containing notes or jottings to be afterward extended in due form.

Business aside from the main business. / Something secondary or subordinate.

A secondary cause.

(theater) Action carried on aside, commonly in dumb show, while the main action proceeds; action not intended to be observed by some of the persons present.

(transitive, intransitive, sometimes figuratively) To pass without being noticed or intercepted.

Alternative form of hoist by one's own petard