tillagen.1. The operation, practice, or art of tilling or preparing land for seed, and keeping the ground in a proper state for the growth of crops.()2. A place tilled or cultivated; cultivated land.()()n.[NL., after Prof. Tillands, of Abo, in Finland.] (Bot.) An immense genus of epiphytic bromeliaceous plants confined to tropical and subtropical America. They usually bear a rosette of narrow overlapping basal leaves, which often hold a considerable quantity of water. The spicate or paniculate flowers have free perianth segments, and are often subtended by colored bracts. Also, a plant of this genus.()