Middle English word thenchen comes from Proto-Indo-European *tong-, and later Proto-Germanic *þankijaną (To perceive, to think.)

Detailed word origin of thenchen

Dictionary entry	Language	Definition
*tong-	Proto-Indo-European (ine-pro)
*þankaz	Proto-Germanic (gem-pro)	Gratitude; thanks. Remembrance. Thought; mind; consideration.
*þankijaną	Proto-Germanic (gem-pro)	To perceive, to think.
þenċean	Old English (ang)
thynken	Middle English (enm)

Words with the same origin as thenchen