Lewis & Short

observantĭa, ae, f. [observo], a remarking, noting, regard, observance.

  1. I. In gen.: temporum observantia, Vell. 2, 1063.
  2. II. In partic.
    1. A. Observance, attention, respect, regard, reverence shown to another: observantia est, per quam aetate, aut sapientiā, aut honore, aut aliquā dignitate antecedentes veremur et colimus, Cic. Inv. 2, 22, 65: officia observantiamque dilexit, id. Balb. 28, 53: tenuiorum, id. Mur. 34, 71: amicos observantiā, rem parsimoniā retinere, id. Quint. 18, 59: observantia, quā me colit, id. Fam. 12, 27, 1: in regem, Liv. 1, 35: eadem pro libertis adversus patronos, Quint. 11, 1, 66.
    2. B. An obedient observance; a keeping, following, performing of laws, customs, etc.: prisci moris observantia, Val. Max. 2, 6, 7: juris, Dig. 1, 2, 2.
      1. 2. An observance of religious duties, divine worship, religion: fides Catholicae observantiae, Cod. Th. 16, 5, 12, § 54: religio et observantia, Vulg. 2 Macc. 6, 11.