English▸ (abase oneself) verb [with object] behave in a way that belittles or degrades (someone):
I watched my colleagues abasing themselves before the board of trustees.
– ORIGIN late Middle English: from Old French abaissier, from a- (from Latin ad ‘to, at’) + baissier ‘to lower’, based on late Latin bassus ‘short of stature’. The spelling has been influenced by base2.