pron. Originally the unstressed form of HEM, dat. and accus. 3rd pers. pl. The emphatic form of the pronoun was early superseded by THEM, but the unstressed form continued to be used, being regarded as an abbreviation of them. In literature it is now obs. or arch., but is still common in familiar speech.
In north midland dialects em may have arisen from them: cf. South Yorkshire at for that. In strictly northern dialects it is never used.
c. 1380. Sir Ferumb., 3098. Þer na ascapedem non.
1599. Shaks., Hen. V., IV. iii. 124. These ioynts as I will leaue vm them.
1672. R. Wild, Poet. Licent., 35. Some men there be that carry all before em.
1702. Eng. Theophrast., 2. New-cast your Poems, purge em of their Dross.
1750. W. Pelham, Lett., in Lady Chatterton, Mem. Adm. Gambier (1861), I. iii. 36. You know my thoughts, I will trouble you therefore no more about em.
1832. Tennyson, Death Old Year. He gave me a friend, and a true true-love. And the New Year will take em away.
1868. Furnivall, Temp. Pref. to Sir-Text Cant. Tales, 41, note. We cant blame em, as we all used to do the same.