Verb
To make thick (in any sense of the word).
To render dense; to inspissate; as, to thicken paint.
To make close; to fill up interstices in; as, to thicken cloth; to thicken ranks of trees or men.
To strengthen; to confirm.
To make more frequent; as, to thicken blows.
To become thick.
Source: Webster's dictionaryThe sauce thickened Source: Internet
The egg yolk will inspissate Source: Internet
Thicken the sauce Source: Internet
inspissate the tar so that it becomes pitch Source: Internet
thicken the sauce by adding flour Source: Internet
A fuller 's shop for preparing woolen cloth (shrink and thicken) was evidently situated further to the west and south, then by the edge of the city. Source: Internet