The definition of a protrusion is something that bulges out or sticks out.(noun)
A hernia that sticks unnaturally out of your skin is an example of a protrusion.
See protrusion in Webster's New World College Dictionary
Origin: < L protrusus (see protrusile) + -ion
See protrusion in American Heritage Dictionary 4
Origin: Latin prōtrūsus
Origin: , past participle of prōtrūdere, to protrude; see protrude
Origin: + -ion.
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