v. t. - To make thick (in any sense of the word).
v. t. - To render dense; to inspissate; as, to thicken paint.
v. t. - To make close; to fill up interstices in; as, to thicken cloth; to thicken ranks of trees or men.
v. t. - To strengthen; to confirm.
v. t. - To make more frequent; as, to thicken blows.
v. i. - To become thick.