The Collaborative International Dictionary of English v.0.48:

Penny \Pen*ny\, n.; pl. Penniesor Pence (p[e^]ns). Pennies
   denotes the number of coins; pence the amount of pennies in
   value. [OE. peni, AS. penig, pening, pending; akin to D.
   penning, OHG. pfenning, pfenting, G. pfennig, Icel. penningr;
   of uncertain origin.]
   1. A former English coin, originally of copper, then of
      bronze, the twelfth part of an English shilling in account
      value, and equal to four farthings, or about two cents; --
      usually indicated by the abbreviation d. (the initial of
      denarius).
      [1913 Webster]

   Note: "The chief Anglo-Saxon coin, and for a long period the
         only one, corresponded to the denarius of the Continent
         . . . [and was] called penny, denarius, or denier."
         --R. S. Poole. The ancient silver penny was worth about
         three pence sterling (see Pennyweight). The old
         Scotch penny was only one twelfth the value of the
         English coin. In the United States the word penny is
         popularly used for cent.
         [1913 Webster]

   2. Any small sum or coin; a groat; a stiver. --Shak.
      [1913 Webster]

   3. Money, in general; as, to turn an honest penny.
      [1913 Webster]

            What penny hath Rome borne,
            What men provided, what munition sent? --Shak.
      [1913 Webster]

   4. (Script.) See Denarius.
      [1913 Webster]

   Penny cress (Bot.), an annual herb of the Mustard family,
      having round, flat pods like silver pennies (Thlaspi
      arvense). Also spelled pennycress. --Dr. Prior.

   Penny dog (Zool.), a kind of shark found on the South coast
      of Britain: the tope.

   Penny pincher, Penny father, a penurious person; a miser;
      a niggard. The latter phrase is now obsolete. --Robinson
      (More's Utopia).

   Penny grass (Bot.), pennyroyal. [R.]

   Penny post, a post carrying a letter for a penny; also, a
      mail carrier.

   Penny wise, wise or prudent only in small matters; saving
      small sums while losing larger; penny-wise; -- used
      chiefly in the phrase, penny wise and pound foolish.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mustard \Mus"tard\, n. [OF. moustarde, F. moutarde, fr. L.
   mustum must, -- mustard was prepared for use by being mixed
   with must. See Must, n.]
   1. (Bot.) The name of several cruciferous plants of the genus
      Brassica (formerly Sinapis), as white mustard
      (Brassica alba), black mustard (Brassica Nigra),
      wild mustard or charlock (Brassica Sinapistrum).
      [1913 Webster]

   Note: There are also many herbs of the same family which are
         called mustard, and have more or less of the flavor of
         the true mustard; as, bowyer's mustard (Lepidium
         ruderale); hedge mustard (Sisymbrium officinale);
         Mithridate mustard (Thlaspi arvense); tower mustard
         (Arabis perfoliata); treacle mustard (Erysimum
         cheiranthoides).
         [1913 Webster]

   2. A powder or a paste made from the seeds of black or white
      mustard, used as a condiment and a rubefacient. Taken
      internally it is stimulant and diuretic, and in large
      doses is emetic.
      [1913 Webster]

   Mustard oil (Chem.), a substance obtained from mustard, as
      a transparent, volatile and intensely pungent oil. The
      name is also extended to a number of analogous compounds
      produced either naturally or artificially.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Thlaspi arvense
    n 1: foetid Eurasian weed having round flat pods; naturalized
         throughout North America [syn: field pennycress, French
         weed, fanweed, penny grass, stinkweed, mithridate
         mustard, Thlaspi arvense]