Alternative form of back-of-the-envelope

plural of back wall

(transitive) To withdraw or backpedal on a statement or promise. / Used other than figuratively or idiomatically: see walk, back.

(American football, Canadian football) Collective term for the defensive players who are in position farthest from the ball at the start of a play and whose principal responsibility is to defend against passes. Includes cornerbacks and safeties in both codes, and defensive halfbacks in the Canadian game.

plural of back straight

To retaliate

Used other than figuratively or idiomatically: see pull, back. / To retreat / To retract / (transitive) to pull in order to reveal something underneath or behind.

(transitive and intransitive with on) To reduce the amount of (something). / (intransitive with on) To reduce spending. / (intransitive with on) To reduce consumption.

plural of back labour

UK spelling of back labor