Third declension adjectives of "one termination" not following the participle pattern:

Ending in s:

Ending in r:

senex: is senium attested as genitive plural?

Ending in l:

  • vigil (are neuter forms actually attested?)

Compounds of corpus, color and pes,

ferox, trux

Attested neuter forms: insontia (pectora, membra, in alia pura & insontia)

See also discussion in


  • "The neuter plural is only formed from those adjectives of one termination, which end in ans and ens, in as (rarely), rs, ax, ix, and ox, and from the numeral adjectives in plex": Latin Grammar by J. N. Madvig, translated by George Woods
  • "victrix, ultrix, and nutrix, though properly feminine substantives, have a neuter in the plural as well as a feminine, as, victrices, victricia.
  • "All those adjectives that have e only in the ablative, have no neuter plural; also, adjectives of one termination in er, es, or, os, and fex, whether the ablative ends in i or e and i, have seldom a neuter plural; as, puber, degener, uber; ales, locuples, deses, reses; memor, concolor, bicorpor; compos, impos, exos; artifex, &c.; also, comis, consors, exors, inops, particeps, princeps, pubis, impubis, redux, sons, insons, supplex, and vigil." Latin Grammar by Richard Hiley
  • "Adjectives ending in er, or, es, os, have no neuter plural; as pauper, memor, dives, compos. Also pubis, impubis, supplex, comis, inops, vigil, sons, insons, redux, intercus, and a few others; except hebes, teres, and adjectives in er of three endings; as pedester." The Eton Latin Grammar