Bol: Letters played on the tabla. Mnemonic syllables and a series of notes produced when stroked. E.g. Na, tin, Dha, Dhin, Ge, Ke, etc.
Tala (or Taal) : Rhythm cycle, It is a measure of dance, vocal/instrument playing.
Example: Dadra Taal, Ada Chautal, Teental, Keherwa, etc.
Matra : When a taal is divided completely (broken into parts), each of the divided part or letter is called a matra.
Lay (or Laya): The tempo, the time gap between each matra of a taal. Three layas are prominent viz.Vilambit, Madhya and Drut.
Sam: The first beat of a tāal.
Vibhag: Taal division.
Khali : Off or no claps.
Theka : A standard series of bols that form the rhythmic basis of tabla accompaniment for a given tala.
Aavartan: The rhythmic cycle from the first matra to the last matra.
Rela : A sort of rapid drum-roll.
Baj, Baaj, or Baaz : A style of playing, different from the gharānā. Two main styles developed, PurbiBaj and DilliBaj. Dilli, or Delhi, baj is the *style of bols and playing that originated in the city of Delhi. Purbi (meaning “eastern”) developed in the area east of delhi. Both have different ways to play bols.
Youtube links : Taal and Tabla demonstration