lighten

Etymology 1

From Middle English lightnen, equivalent to light + -en.

verb

1. (transitive) To make brighter or clearer; to illuminate.
   to lighten an apartment with lamps or gas; to lighten the streets
   A Key of fire ran all along the shore, And lighten’d all the river with the blaze: 1667, John Dryden, Annus Mirabilis, London: Henry Herringman, stanza 231, p. 59
2. (intransitive) To become brighter or clearer; to brighten.
3. (intransitive, now rare) To flash lightning, to give off lightning.
   While we were in the Twins it began to thunder and lighten and pour with rain. 1986, Helen Garner, Yellow Notebook: Diaries 1978-1987, Text Publishing, published 2022, page 182
4. (transitive) To emit or disclose in, or as if in, lightning; to flash out, like lightning.
5. To illuminate with knowledge; to enlighten.
   O Light which mak’st the Light, which makes the Day, Which setst the Eye without and Mind within, Lighten my spirit with one cleare heavenly ray, Which now to view it selfe doth first begin. 1599, John Davies, “Of the Soule of man, and the immortalitie thereof”, in Nosce Teipsum. This Oracle Expounded in Two Elegies, London: John Standish, page 10

Etymology 2

From Middle English lightnen, equivalent to light + -en.

verb

1. (transitive) To alleviate; to reduce the burden of.
   Sorrow can be lightened by being openly brought out.
2. (transitive) To make light or lighter in weight.
3. (transitive) To make less serious or more cheerful.
4. (intransitive) To become light or lighter in weight.
5. (intransitive) To become less serious or more cheerful.

Etymology 3

From light + -en.

verb

1. To descend; to light.
   Book of Common Prayer O Lord, let thy mercy lighten upon us.