Lewis & Short

auctumnĭtas (correctly aut-), ātis, f. [auctumnus] (only ante- and post-class.).

  1. I. The season of autumn, the autumn, harvest-time: Circum oleas autumnitate ablaqueato, Cato, R. R. 5, 8: primā autumnitate cum pluvius est, id. ib. 155, 1: autumnitas in anni tetrachordo mensem praeterierat, Varr. ap. Non. p. 71, 15: aestas atque autumnitas, Arn. 2, p. 96.
  2. II. The produce of autumn, the harvest (cf. 1. auctumnus, II.): dapem autumnitatis uvidam, Varr. ap. Non. p. 71, 18: ex olivis atque vinetis plenam faciant autumnitatem fundi, Arn. 1, p. 12.