Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. tonsus, a, um, Part. of tondeo.
2. tonsus, ūs, m. [tondeo], the cut or mode of dressing the hair (ante-class.): pes, statura, tonsus, oculi, etc., Plaut. Am. 1, 1, 288: mulier tonsu lugubri, Att. ap. Non. 179, 20.