The Collaborative International Dictionary of English v.0.48:

Hemorrhoids \Hem"or*rhoids\, n. pl. [L. haemorrhoidae, pl., Gr.
   ?, sing., ? (sc. ?), pl., veins liable to discharge blood,
   hemorrhoids, fr. ? flowing with blood; a"i^ma blood + ? to
   flow: cf. F. h['e]morro["i]des, h['e]morrho["i]des. See
   Rheum.] (Med.)
   Livid and painful swellings formed by the dilation of the
   blood vessels around the margin of, or within, the anus, from
   which blood or mucus is occasionally discharged; piles;
   emerods.

   Usage: [The sing. hemorrhoid is rarely used.]
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Piles \Piles\, n. pl. [L. pila a ball. Cf. Pill a medicine.]
   (Med.)
   The small, troublesome tumors or swellings about the anus and
   lower part of the rectum which are technically called
   hemorrhoids. See Hemorrhoids.

   Note: [The singular pile is sometimes used.]
         [1913 Webster]

   Blind piles, hemorrhoids which do not bleed.
      [1913 Webster]