Lewis & Short

quincuncĭālis, e, adj. [quincunx].

  1. I. Containing five twelfths of a whole (of a foot, etc.): quincuncialis magnitudo, the size of five twelfths of a foot, Plin. 9. 48, 72, § 155: herba, five twelfths of a foot high, id. 27, 11, 74, § 98.
  2. II. In partic., planted in the form of a quincunx: quincuncialis ordinum ratio, Plin. 17, 11, 15, § 78.