Fals

According to the Old English Dictionary:

fals

adj. False (of weight or coinage) :-- Fals pening (printed flas pennig) (or? fals-pening, cf. Icel. fals-penningr) paracaraximus, Wrt. Voc. i. 57, 34. Swicollice dǽda and láðlice unlaga áscunige man swýðe; ꝥ is false gewihta and wóge gemeta, Ll. Th. i. 310, 13. Wóge gemeta and false gewihta rihte man georne, Wlfst. 272, 4. fals