forming verbs.
1. from adjs., as darken, deepen, harden, madden, moisten, widen. Most of the words of this type seem to have been formed in late ME. or early mod.Eng., on the analogy of a few verbs which came down from OE. or were adopted from ON.; e.g., fasten:—OE. fæstnian: ? brighten:—ONorthumb. berhtnia; harden:—ON. harðna. In Teut. there are two classes of vbs. formed upon the ‘weak’ or lengthened stems of adjs. (suffix -on-): (a) the intransitive (or in sense pass.) vbs. which in Goth. make the inf. in -nan, and the pa. t. in -ôda; e.g., fullnan to be filled, f. fullan- full; gabignan to be rich, f. gabigan- rich; managnan to abound, f. managan- many; (b) the originally trans. vbs. in OTeut. (i)nôjan, e.g., OHG. festinôn to fasten, f. feston- (:—fastjon-) fast. In Eng. these two classes of vbs. can scarcely be discriminated with precision, but in most cases the intr. sense (as in deepen = ‘become deeper’) appears to be derived from the trans. sense (as in deepen = ‘make deeper’).
2. from sbs. In OTeut. sbs. both of the weak and the strong declension gave rise to intr. verbs in -(i)nôjan, and this formation is represented by a few examples in OE., such as hlystnian to LISTEN. In 14th c. some additional vbs. occur, formed app. on the analogy of these, as happen, threaten. The majority of Eng. words f. sb. + -en, however, such as heighten, lengthen, strengthen, hearten, barken, appear first in mod.Eng., and seem to be due to the analogy of the verbs f. adjs.
3. In one or two cases (e.g., waken) the suffix -en represents Teut. -na-, the formative of the present stem in certain strong verbs.
