late 14c. (transitive), 1590s (intransitive), from thick + -en (1). Related: Thickened; thickening. An earlier verb was Middle English thick, Old English þiccian "to thicken, to crowd together."
The sauce thickened
thicken the sauce by adding flour
thew
thews
they
thiamin
thick
thicken
thickening
thicket
thickness
thickset
thief
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