simple past tense and past participle of kill two birds with one stone

To have another means or expedient kept in reserve in case the current one fails.

(idiomatic) never

(physics, chemistry) a phase of water ice which is two-dimensional, amorphous, and may shrink during freezing, unlike most forms of water ice

plural of three-center two-electron bond

(New England, nautical, idiomatic) Said of an unwisely or overly extravagant person.

(idiomatic) Synonym of kill two birds with one stone

(music, very rare) A note played for 1⁄256 of the duration of a whole note.

Every situation has two sides.

plural of two hundred fifty-sixth note