Chapter 6: Turning Latin Adjectives into Latin Nouns

§46. The Latin suffix -ITAS (> E -ity); variant -ETAS (> E -ety)

In terms of frequency, this suffix is to Latin noun formation what -alis is to Latin adjective formation. The morpheme -itas was regularly attached to the base of Latin adjectives to form literally hundreds of abstract nouns, almost all of which, it seems, have survived as English derivatives ending in -ity. The historical process is so dependable that you can confidently reconstruct a Latin noun in -itas for almost any English word in -ity. What is more, you can then remove the -itas suffix from the Latin noun to uncover its adjective base. If you can then discern the meaning of that Latin adjective, you will know the ETYMOLOGICAL MEANING of the English word. This type of exercise is very good for building English vocabulary.

We’ll begin with a group of ordinary Latin adjectives—some familiar to you, others presented here for the first time. As you see how each one became first a Latin noun and then (many centuries later) an English derivative, there should hardly be any need for comment or explanation:[1]

L sanus (“sound”)  > sanitas (“soundness”)  > E sanity
clarus (“bright”) > claritas (“brightness”) > clarity
dignus (“worthy”) > dignitas (“worthiness”) > dignity
vacuus (“empty”) > vacuitas (“emptiness”) > vacuity
brevis (“short”) > brevitas (“shortness”) > brevity
gravis (“heavy”)  > gravitas (“heaviness”)  > gravity

Conversely, then, we can reconstruct the ancestry of almost any English noun that ends in -ty, working back to an original Latin adjective and a useful etymological meaning:

E acerbity < L noun acerbitas < L adj. acerbus (“bitter”) ∴ E acerbity = “bitterness”
verity  < veritas < verus (“true”)  ∴ verity = “truth”
sanctity  < sanctitas < sanctus (“holy”)  ∴ sanctity = “holiness”
levity  < levitas < levis (“light”)  ∴ levity = “lightness”
maturity  < maturitas < maturus (“ripe”)  ∴ maturity = “ripeness”

Sometimes the English derivative has been further modified in form because of phonetic factors in its transmission. The noun charity, for instance, comes from Latin caritas (< carus, “dear”); it manifests the now-familiar change from ca- to cha- that occurred in the Old French period. English cruelty is even more transformed, having evolved from Latin crudelitas (< crudelis, “cruel”). In these cases, the source-word can hardly be predicted without prior knowledge of Latin. But there is nothing surprising about the development of E equity from L aequitas (< aequus, “level,” “fair”), since the Latin diphthong ae is regularly reduced to e in English.

Here is an interesting feature of Latin nouns in -itas. Just as this suffix can turn a simple adjective into a derived noun (as we have been observing), so can it be added to the base of a derived adjective to create a new derived noun. Consider these examples:

L vita > vitalis (base vital-) > vital-itas > E vitality
mors, mort-is > mortalis (base mortal-) > mortal-itas > mortality
verbum > verbosus (base verbos-) > verbos-itas > verbosity
urbs, urb-is > urbanus (base urban-) > urban-itas > urbanity
vir > virilis (base viril-) > viril-itas > virility

This process (noun → adjective → noun) is not uncommon in native English word formation: Germanic live-li-ness is structurally parallel to Latinate vit-al-ity, word-i-ness to verb-os-ity, and man-li-ness to vir-il-ity.[2]

We saw in Chapter 5 that the adjective suffix -alis has a phonetic variant in -aris. The noun suffix -itas has two phonetic variants. Neither of these is very different from the main type, and both are reflected precisely in their English derivatives:

  • If the adjective base ends in -i-, the suffix is not -itas but -etas (> E -ety):
L vari-us (“diverse”) > vari-etas > E variety
pi-us (“dutiful,” “good”) > pi-etas > piety[3]
propri-us (“one’s own”) > propri-etas > propriety
soci-us (“united,” “allied”) > soci-etas > society
dubi-us (“doubtful”) > dubi-etas > dubiety
sobri-us (“sober”) > sobri-etas > sobriety


  • If the adjective base ends in -r- or -t-, the derived noun will end in -tas (> E –ty):
L liber (“free”) > liber-tas > E liberty
puber (“adult”) > puber-tas > puberty
honestus (“honourable”) > honestas > honesty


  1. The examples given here represent a deliberate oversimplification. There were several important historical steps between, say, L gravitas and E gravity. The normal progression was Latin -tatem (accusative form) > Old French -tet > OF -te [mod F -] > Middle English -tie > Modern English -ty.
  2. Just because two English words are structural or etymological parallels, they will not necessarily be synonyms. Element for element, the Latin derivative formality is closely parallel to the native English word shapeliness, but they are not remotely similar in dictionary meaning.
  3. The negation of pius is im-pi-us (“wicked”) > im-pi-etas > E impiety; similarly, the negation of proprius is L im-propri-us (“improper”) > im-propri-etas > E impropriety.


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Greek and Latin Roots: Part I - Latin by Peter Smith (Estate) is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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