The Collaborative International Dictionary of English v.0.48:

Pirl \Pirl\, v. t. [Cf. Purl.]
   1. To spin, as a top.
      [1913 Webster]

   2. To twist or twine, as hair in making fishing lines.
      [1913 Webster]

The Free On-line Dictionary of Computing (30 December 2018):

PIRL

   Pattern Information Retrieval Language.

   A language for digraph manipulation, embeddable in Fortran
   or ALGOL, for IBM 7094.

   ["PIRL - Pattern Information Retrieval Language",
   S. Berkowitz, Naval Ship Res Dev Ctr, Wash DC].

   (1994-11-29)