Middle English word swynden comes from Proto-Indo-European *swey-, and later Proto-Germanic *swindaną (To dwindle.)

Detailed word origin of swynden

Dictionary entry	Language	Definition
*swey-	Proto-Indo-European (ine-pro)	to twist, swing
*swindaną	Proto-Germanic (gem-pro)	To dwindle.
swindan	Old English (ang)	To waste away, languish, grow languid, be consumed.
swynden	Middle English (enm)

Words with the same origin as swynden