noun

• (archaic) One beloved; a lover, a sweetheart of either sex (especially a secret lover; a gallant or mistress).
  "Faire Venus seemde vnto his bed to bring Her, whom he waking euermore did weene, To be the chastest flowre, that ay did spring On earthly braunch, the daughter of a king, Now a loose Leman to vile seruice bound[…]."
• (often pejorative) A paramour.
  "'...They are lost, I tell thee, they are lost. For them there is no heaven nor hell, and in neither shall they praise God’s name.’ ‘Father,’ cried the young Fisherman, ‘thou knowest not what thou sayest. Once in my net I snared the daughter of a King. She is fairer than the morning star, and whiter than the moon. For her body I would give my soul, and for her love I would surrender heaven. Tell me what I ask of thee, and let me go in peace.’ ‘Away! Away!’ cried the Priest: ‘thy leman is lost, and thou shalt be lost with her.’ And he gave him no blessing, but drove him from his door."