Present participle; Past participle - thickening - thickened Present - thicken - thicken - thickens - thicken - thicken - thicken Past - thickened - thickened - thickened - thickened - thickened - thickened Future - will thicken - will thicken - will thicken - will thicken - will thicken - will thicken Present conditional - would thicken - would thicken - would thicken - would thicken - would thicken - would thicken Present Perfect - have thickened - have thickened - has thickened - have thickened - have thickened - have thickened Past Perfect - had thickened - had thickened - had thickened - had thickened - had thickened - had thickened Future Perfect - will have thickened - will have thickened - will have thickened - will have thickened - will have thickened - will have thickened Past conditional - would have thickened - would have thickened - would have thickened - would have thickened - would have thickened - would have thickened Imperative - - - thicken - - - - - - - -