os·ti·na·to 
(ŏs′tĭ-nätō)
(ŏs′tĭ-nätō)n. pl. os·ti·na·tos
A short melody or pattern that is constantly repeated, usually in the same part at the same pitch.
[Italian, from Latin obstinātus, stubborn, past participle of obstināre, to persist; see OBSTINATE.]