Antonyms of verb thicken

2 of 3 senses of thicken

Sense 1
thicken, inspissate -- (make thick or thicker; "Thicken the sauce"; "inspissate the tar so that it becomes pitch")
       Antonym of thin (Sense 2)
      => thin -- (make thin or thinner; "Thin the solution")

Sense 2
thicken, inspissate -- (become thick or thicker; "The sauce thickened"; "The egg yolk will inspissate")
       Antonym of thin (Sense 1)
      => thin -- (lose thickness; become thin or thinner)

Synonyms/Hypernyms (Ordered by Estimated Frequency) of verb thicken

3 senses of thicken

Sense 1
thicken, inspissate -- (make thick or thicker; "Thicken the sauce"; "inspissate the tar so that it becomes pitch")
       => change, alter, modify -- (cause to change; make different; cause a transformation; "The advent of the automobile may have altered the growth pattern of the city"; "The discussion has changed my thinking about the issue")

Sense 2
thicken, inspissate -- (become thick or thicker; "The sauce thickened"; "The egg yolk will inspissate")
       => change state, turn -- (undergo a transformation or a change of position or action; "We turned from Socialism to Capitalism"; "The people turned against the President when he stole the election")

Sense 3
thicken, inspissate -- (make viscous or dense; "thicken the sauce by adding flour")
       => change integrity -- (change in physical make-up)