(slang, MLE, MTE) A secondary lover, a mistress.

plural of epistle side

Angry words, harsh criticism.

plural of side letter

(law) A collective bargaining agreement that is not part of the underlying or primary collective bargaining agreement used by the parties to the contract.

Alternative form of onside

plural of country-side

To be able to laugh at another person through having got the better of them.

Synonym of laugh on the other side of one's face

Of a stance in which something is positioned at right angles to its expected orientation.