Lewis & Short

praesentānĕus, a, um, adj. [praesens].

  1. I. Momentary, instantaneous (late Lat.): commotio, Lact. de Ira Dei, 21, 8.
  2. II. That operates quickly or immediately (post-Aug.): remedium, Plin. 21, 31, 105, § 180: venenum, id. 24, 1, 1, § 2: (remedium) quam posset velocissimum ac praesentaneum coquere, Suet. Ner. 33; Sen. Ep. 95, 25.
    Subst.: praesentānĕum, i, n., a remedy that operates quickly, Plin. 30, 9, 23, § 79.
    Adv.: praesentānĕē, forthwith, immediately (post-class.), Theod. Prisc. ad Tim. Fr. praef. 1.