Etymology Dictionary

LACK (1),  want.  (O. Low G.)   The old sense is often 'failing,' 'failure,' or 'fault.'   M. E. lak, spelt lac, Havelok, l. 191; the pl. lakkes is in P. Plowman, B. x. 262.   Not found in A. S., but an Old Low G. word.   Cf. Du. lak, blemish, stain; whence laken, to blame.   We also find Icel. lakr, defective, lacking.   β. Fick connects Icel. lakr with Icel. leka, to leak (iii. 261).   In this view lack is a defect or leak; see Leak.   We find A. S. læc, wounded (Grein, ii. 161), a rare word, which agrees with the Du. adj. lek, leaky, G. leck, leaky.   ¶ There is no reason for connecting E. lack with Goth. laian, to revile; for this answers to A. S. leán, to revile, which is quite a different word.   Der. lack, verb; see below.

LACK (2),  to want, be destitute of.  (O. Low G.)   M. E. lakken, Chaucer, C. T. 758, 11498; P. Plowman, B. v. 132.   The verb is formed from the sb., not vice versâ; this is shewn by the O. Fries. lakia, to attack, blame, where the suffix -ia is the usual one in the case of a causal verb formed from a sb.   Hence the verb is a weak one; and the pt. t. is lakkede, as in Chaucer.   See therefore Lack (1) above.