deinstrumental

Recently Weiss (2009: 303–5) delineated in his Outline a clear sketch of the steps by which the Latin group in -et- originated by composition and analogy, and identified three subgroups (deverbal, denominal, deinstrumental) with different origins among the nouns in simple d.

2016, Lothar Willms, “On the origin of Latin suffixes in -d- and -es, -itis”, in Indogermanische Forschungen, volume 121, number 1, →DOI, page 93

A highly characteristic subtype of the general case just mentioned (athematic base plus complex thematic suffix) appears in so-called “deinstrumental” adjectival formations: thus astū ‘cleverly’ (u-stem instr. sg. *-u-h₁, i.e. ‘with cleverness’) → astūtus ‘clever’, similarly -ītus adjectives based on i-stem instr. sg. *-i-h₁ (aurītus ‘having ears’, cf. auris ‘ear’), -ōtus adjectives based on o-stem instr. sg. *-o-h₁ (aegrōtus ‘sick’, cf. aegrum ‘distress’); likewise, with instr. sg. plus *-no-, adjectival suffix conglomerates -īnus, -ūnus, -ōnus etc. (cf. Weiss 2011: 290, 293, and further 7.3.1.3 on futūrus).

2017, Brent Vine, “The morphology of Italic”, in Jared Klein, Brian Joseph and Matthias Fritz, editors, Volume 2 Handbook of Comparative and Historical Indo-European Linguistics: An International Handbook, De Gruyter Mouton, page 780