Core of the cigar: the leaves bunched inside the binder that supply most of the tobacco volume and the backbone of the blend. Filler is normally a mix of leaf classes and origins balanced for strength, aroma, and combustion.
Why it matters
Filler blend determines strength and much of the flavor arc, while the way those leaves are folded determines whether the cigar draws freely.
In context
"The tripa is three Nicaraguan leaves plus a little Dominican piloto for sweetness."