To act in a manner below oneself; to debase oneself.
To remove a part, to detract from (a quality of excellence, authority etc.).
To take away (something from something else) in a way which leaves it lessened.
To detract from (something); to disparage, belittle.
To perceive (someone or something) as having a lower value, quantity, worth, etc., than what he/she/it actually has.
An estimate that is too low.