[Ciliophora] Hypotrichids: compound somatic ciliature. Cluster of cilia functioning as single unit but with no common enveloping membrane. Subtypes identified by location: buccal, frontal, frontoterminal, frontoventral, midventral, pretransverse, transverse, marginal and caudal cirri (Ci 7C).

[Polychaeta] Sensory appendage which is usually slender and cylindrical (body plan pelagic polychaete; anterior region ventral view ).

Alternative form for Cirrus : Cirri (pl.).