Synonym of up one's sleeve

A poker hand that contains two cards of one rank, plus three cards which are not of this rank nor the same as each other.

(simile, literary) In a unified manner.

(computing, informal) Binary code; on and off bits.

Synonym of of one's choice

Performing as well as one can.

(idiomatic) In a single attempt with no breaks.

plural of one-dayer

Placed in a situation where one's best behaviour is necessary or advisable.

(golf) A handicap of one stroke every second hole.