The base type *crassia 'fat' is the collective noun to the Latin adjective crassius 'thick, fat', a variant of the Classical Latin form crassus (cf. DELI 2: 517). From the 3rd century onwards, this variant displaced pinguis, which was originally used throughout Romania, and yet is well preserved in the VerbaAlpina area (cf. lmo. pench 'buttermilk' or roh. paintg 'butter' (cf. pinguĕ(m)). The anlaut of the forms preserved in Romanic (gr-) may have been influenced by Latin grossus 'thick', which is not attested in Classical Latin (cf. FEW, 2, 1277-1286, under crassus and Georges under grossus). However, similar sonorisations are also found elsewhere (cf., e.g, crama).
In the Alpine region, this base type occasionally yielded terms for RAHM, i.e. the fatty part of the milk.