Lewis & Short

singŭlārĭtas, ātis, f. [singularis].

  1. I. In gen., a being alone or single, singleness (post-class.), Tert. adv. Valent. 37; id. Anim. 13; id. Exhort. ad Cast. 1; Salv. Cont. Avar. 7, p. 70.
  2. II. In partic., in gram., the singular number, Charis. p. 72 P.
  3. III. In arithmetic, unity, the number one: singularitas omnibus mensura communis, Mart. Cap. 7, §§ 750 and 774.