A vanilla slice.

(games) A children's game in which two people alternately clap their own and each other's hands, often to the accompaniment of the nursery rhyme Pat-a-cake, pat-a-cake, baker's man.

Happening slowly and with plenty of warning; not sudden.

(anatomy) A cleft or gap between two symmetrical parts, particularly between the vocal folds. / (astronomy) A crack or fissure on a lunar or planetary surface; a rille.