The Collaborative International Dictionary of English v.0.48:

Pen \Pen\, v. t. [imp. & p. p. Penned; p. pr. & vb. n.
   Penning.]
   To write; to compose and commit to paper; to indite; to
   compose; as, to pen a sonnet. "A prayer elaborately penned."
   --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pen \Pen\, v. t. [imp. & p. p. Pennedor Pent (?); p. pr. &
   vb. n. Penning.] [OE. pennen, AS. pennan in on-pennan to
   unfasten, prob. from the same source as pin, and orig.
   meaning, to fasten with a peg.See Pin, n. & v.]
   To shut up, as in a pen or cage; to confine in a small
   inclosure or narrow space; to coop up, or shut in; to
   inclose. "Away with her, and pen her up." --Shak.
   [1913 Webster]

         Watching where shepherds pen their flocks at eve.
                                                  --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Penned \Penned\, a.
   1. Winged; having plumes. [Obs.]
      [1913 Webster]

   2. Written with a pen; composed. "Their penned speech."
      --Shak.
      [1913 Webster]

   3. Enclosed in a pen; -- of animals.
      [PJC]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "penned":
   autograph, autographic, barred, beleaguered, beset, besieged,
   blockaded, bound, cabined, caged, calligraphic, chirographic,
   cloistered, closed-in, confined, cooped, cordoned, cordoned off,
   corralled, cramped, cribbed, cursive, enclosed, engrossed, fenced,
   flowing, graphic, graphoanalytic, graphologic, graphometric,
   hedged, hemmed, holograph, holographic, immured, imprisoned,
   in longhand, in shorthand, in writing, incarcerated, inscribed,
   italic, italicized, jailed, leaguered, longhand, manuscript, mewed,
   on paper, paled, penciled, pent-up, printed, quarantined, railed,
   restrained, running, scriptorial, scriptural, shorthand, shut-in,
   stylographic, walled, walled-in, written