Swynken (v.) - to toil, to labor.
What sholde he studie and make hymselven wood,
Upon a book in cloystre alwey to poure,
Or swynken with his handes, and laboure,
As austyn bit? how shal the world be served?
Lat austyn have his swynk to hym reserved!
- Chaucer, Geoffrey: The Canterbury tales (1387-1394)
The Middle-English Word of the Day is selected from Mayhew and Skeat's
"Concise Dictionary of Middle English."
As found on Greg Lindahl's website
The example text was found at the Middle English Collection of the University of Virginia Library.