IPA: /ˈθɪkən/
KK: /ˈθɪkən/
To make something denser or more solid by adding a substance or by cooking it longer.
You can thicken the soup by adding some flour.
Past: thickened
Past Participle: thickened
Thicken → It is formed from "thick" (from Old English "þicce", meaning having a relatively large distance between opposite sides) and "-en" (a suffix used to form verbs indicating to make or become). The word "thicken" means to make something thicker or to become thicker.
Think of making something 'thicker' — 'thick' describes the quality, and '-en' means to make it so.