egomaniac

As an adjective egotistic

is egotistical.

As a noun egomaniac is

a person obsessed with their own (supposed) importance.

As a noun egomaniac

is a person obsessed with their own (supposed) importance.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between egomaniac and megalomaniac

is that egomaniac is a person obsessed with their own (supposed) importance while megalomaniac is one affected with or exhibiting megalomania.

As an adjective egomaniacal

is having the psychological condition of egomania.

As a noun egomaniac is

a person obsessed with their own (supposed) importance.

As nouns the difference between egomaniac and egoist

is that egomaniac is a person obsessed with their own (supposed) importance while egoist is an advocate of egoism.

As a noun egomaniac is

a person obsessed with their own (supposed) importance.

As nouns the difference between egomaniac and egotist

is that egomaniac is a person obsessed with their own (supposed) importance while egotist is a person who talks excessively about his or her self.

As nouns the difference between narcissist and egomaniac

is that narcissist is person full of egoism and pride while egomaniac is a person obsessed with their own (supposed) importance.

As nouns the difference between egomanias and egomaniac

is that egomanias is while egomaniac is a person obsessed with their own (supposed) importance.

As nouns the difference between egomania and egomaniac

is that egomania is excessive vanity, pride or arrogance; self-importance while egomaniac is a person obsessed with their own (supposed) importance.