The Collaborative International Dictionary of English v.0.48:

Pamphlet \Pam"phlet\ (p[a^]m"fl[e^]t), n. [OE. pamflet,
   pamfilet, paunflet, possibly fr. OF. palme the palm of the
   hand, F. paume (see Palm) + OF. fueillet a leaf, dim. of
   fueil, m., F. feuille, f., fr. L. folium, pl. folia, thus
   meaning, a leaf to be held in the hand; or perh. through old
   French, fr. L. Pamphila, a female historian of the first
   century who wrote many epitomes; prob., however, fr. OF.
   Pamflette, the Old French name given to Pamphilus, a poem in
   Latin verse of the 12th century, pamphlets being named from
   the popularity of this poem.]
   1. A writing; a book. --Testament of love.
      [1913 Webster]

            Sir Thomas More in his pamphlet of Richard the
            Third.                                --Ascham.
      [1913 Webster]

   2. A small book consisting of a few sheets of printed paper,
      stitched together, often with a paper cover, but not
      bound; a short essay or written discussion, usually on a
      subject of current interest.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pamphlet \Pam"phlet\ (p[a^]m"fl[e^]t), v. i.
   To write a pamphlet or pamphlets. [R.] --Howell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pamphlet
    n 1: a small book usually having a paper cover [syn: booklet,
         brochure, folder, leaflet, pamphlet]
    2: a brief treatise on a subject of interest; published in the
       form of a booklet [syn: tract, pamphlet]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "pamphlet":
   ad, advert, advertisement, bill, booklet, brochure, bulletin,
   chapbook, circular, comic book, essay, flyer, folder, hand-out,
   handbill, leaflet, notice, tract