grump

As nouns the difference between taxonomy and grump

is that taxonomy is the science or the technique used to make a classification while grump is a habitually grumpy or complaining person.

As a verb grump is

to complain.

As a noun grump

is a habitually grumpy or complaining person.

As a verb grump

is to complain.

As an interjection grumpity is

nonce variation of the word grump, usually used as an intensifier.