Sikerliche (adv.) - surely, certainly.
This lord, which herde of this tempeste
That he tofore his gate blew,
Tho wiste he be the lawe and knew
That he was sikerliche ded:
And as of help he wot no red,
Bot sende for hise frendes alle
And tolde hem how it is befalle.
- Gower, John: Confessio amantis (1390-1393)
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.