A fixed composition — composed once, transmitted exactly, and presented rather than systematically developed. Gats are the jewels of the Purab (Lucknow-Farrukhabad) solo tradition: often asymmetric, full of internal surprises, cast in types like dupalli and tipalli (two- and three-speed designs) or manjhedar (mid-cycle entries).
Unlike a kaida, a gat is not a rule-system to expand; its interest is architectural. Players present it, perhaps repeat it so the ear catches the design, and close with its tihai. Note the parallel use in melody: a sitarist's gat is the fixed melodic composition — same word, same idea.