The Collaborative International Dictionary of English v.0.48:

Parol \Pa*rol"\, n. [See Parole, the same word.]
   [1913 Webster]
   1. A word; an oral utterance. [Obs.]
      [1913 Webster]

   2. (Law) Oral declaration; word of mouth; also, a writing not
      under seal. --Blackstone.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Parol \Pa*rol"\, a.
   Given or done by word of mouth; oral; also, given by a
   writing not under seal; as, parol evidence.
   [1913 Webster]

   Parol arrest (Law), an arrest in pursuance of a verbal
      order from a magistrate.

   Parol contract (Law), any contract not of record or under
      seal, whether oral or written; a simple contract.
      --Chitty. Story.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "parol":
   articulated, enunciated, lingual, linguistic, linguistic act,
   locution, nuncupative, oral, parole, phonation, pronounced, said,
   sequence of phonemes, sounded, speaking, speech, speech act,
   spoken, string, the spoken word, tongue, unwritten, utterance,
   utterance string, uttered, verbal, viva voce, vocable, vocal,
   vocalized, voice, voiced, voiceful, word, word of mouth



Bouvier's Law Dictionary, Revised 6th Ed (1856):

PAROL. More properly parole. A French word, which means literally, word or
speech. It is used to distinguish contracts which are made verbally or in
writing not under seal, which are called, parol. contracts, from those which
are under seal which bear the name of deeds or specialties (q.v.) 1 Chit.
Contr. 1; 7 Term. R. 3 0 351, n.; 3 Johns. Cas. 60; 1 Chit. Pl. 88. It is
proper to remark that when a contract is made under seal, and afterwards it
is  modified verbally, it becomes wholly a parol contract. 2 Watts, 451; 9
Pick. 298; 13 Wend. 71.
     2. Pleadings are frequently denominated the parol. In some instances
the term parol is used to denote the entire pleadings in a cause as when in
an action brought against an infant heir, on an obligation of his ancestors,
he prays that the parol may demur, i. e., the pleadings may be stayed, till
he shall attain full age. 3 Bl. Com. 300; 4 East, 485 1 Hoffm. R. 178. See a
form of a plea in abatement, praying that the parol may demur, in 1 Wentw.
Pl. 43; and 2 Chit. Pl. 520. But a devisee cannot pray the parol to demur. 4
East, 485.
     3. Parol evidence is evidence verbally delivered by a witness. As to
the cases when such evidence will be received or rejected, vide Stark, Ev.
pt. 4, p. 995 to 1055; 1 Phil. Ev. 466, c. 10, s. 1; Sugd. Vend. 97.