sen·sil·lum 
(sĕn-sĭləm)
(sĕn-sĭləm)n. pl. sen·sil·la (-sĭlə)
A simple sense organ of an arthropod or other invertebrate that consists of one cell or a few cells and may take the form of a hair or bristle.
[New Latin sēnsillum, diminutive of Latin sēnsus, sense; see SENSE.]