Many English words with Latin origins contain the string of letters <it>. Sometimes the <it> is a suffix; sometimes not. For example, do the words addition, apparition, cognition, debit, edit, explicit, fruit, fugitive, implicit, incondite, infinite, inquisition, inquisitive, posit, position, prerequisite, and unite have an -it(e) suffix? What about gravitate and levitate? Or words like acidity, dignity, and infinity? Uncovering the -it(e) suffix requires an understanding of Latin verbs and the etymology of specific words.
The -it(e) suffix in Modern English comes from the -itus past participle ending of Latin verbs. The Latin past participle ending -itus also formed adjectives that often described a state or condition resulting from an action. (English similarly has participial adjectives.) Over time, the -itus ending evolved into the English -it(e) suffix. Consider the morphology and etymology of the following words:
ad + D + it(e) + ion → addition, from Latin addere (additus)
e + D + it(e) → edit, from Latin ēdere (ēditus)
e + D + it(e) + ion → edition, from Latin ēdere (ēditus)
in + con + D + it(e) → incondite, from Latin inconditus, from condere (conditus)
ap + Pare + it(e) + ion → apparition, from Latin appārēre (appāritus)
co + Gn + it(e) + ion → cognition, from Latin cognōscere (cognitus)
Debe + it(e) → debit, from Latin dēbēre (dēbitus)
ex + Plice + it(e) → explicit, from Latin explicitus (form of explicātus, from explicāre, from plicāre)
im + Plice + it(e) → implicit, from Latin implicitus (form of implicātus, from implicāre, from plicāre)
Fru + it(e) → fruit, from Latin fruī (fruitus)
Fuge + it(e) + ive → fugitive, from Latin fugere (fugitus)
in + Fine + it(e) → infinite, from Latin īnfīnītus, from fīnīre (fīnītus)
in + Quise + it(e) + ion → inquisition, from Latin inquīsītus, from inquīrere
in + Quise + it(e) + ive → inquisitive, from Latin inquīsītus, from inquīrere
pre + re + Quise + it(e) → prerequisite, from Latin requīsītus, from requīrere
Pose + it(e) → posit, from Latin positus, from pōnere
Pose + it(e) + ion → position, from Latin positus, from pōnere
Une + it(e) → unite, from Latin ūnīre (ūnītus)
Notice that all these words ultimately come from a Latin past participle with an -itus ending. Thus, the -it(e) in Modern English is a Latin stem suffix from the Latin -itus.
As an additional note (pun intended), the suffix -it(e) written with a parenthetical <e> allows for words such as both edit and incondite. In a word such as edit, the -it(e) surfaces as -it. In a word such as incondite, the -it(e) surfaces as -ite. But both the -it and -ite ultimately come from the Latin -itus. Furthermore, words such as edition that contain another vowel-initial suffix after the -it(e) could have either the -it or -ite suffix. The parenthetical -it(e) allows for simultaneous representation of both -it and -ite.
What about words such as gravitate, levitate, acidity, dignity, and infinity? The words gravitate and levitate are newer words, developing during the Early Modern English period. Thus, both words do not come directly from Latin sources. The Latin sources of gravitate and levitate are gravitās and levitās, which consist of gravis + -tās and levis + -tās. The -tās endings developed into -ty in Modern English, resulting in gravity and levity or <Grave + i + ty> and <Leve + i + ty>. The Latin adjectives gravis and levis do not have corresponding *gravire and *levire verbs that have *gravitus and *levitus past participles. Therefore, the words gravitate and levitate do not contain the -it(e).
Two possible analyses thus exist for words such as gravitate and levitate. Because the Latin sources are gravitās and levitās, the new bound bases <Gravite> and <Levite> could arise, leaving the morphology of gravitate and levitate as <Gravite + ate> and <Levite + ate>. However, then the connection with the <Grave> and <Leve> bound bases is lost. <Gravite> and <Levite> become related bases of <Grave> and <Leve>, which is an adequate analysis.
Grave + i + ty → gravity, from Latin gravitās, from gravis + -tās
Leve + i + ty → levity, from Latin levitās, from levis + -tās
Gravite + ate → gravitate, from gravity + ate, from Latin gravitās + ate
Levite + ate → levitate, from levity + ate, from Latin levitās + ate
However, because gravitate and levitate are modern words, formed through gravity + ate and levity + ate, a chronological analysis uncovers a modern suffixal construction: -itate. While gravitate and levitate come from gravity + ate and levity + ate, the morphology is not *<Grave + i + ty + ate> and *<Leve + i + ty + ate>, which would result in the nonexistent words *gravitiate and *levitiate. Instead, the modern suffix -itate is morphologically unanalyzable but etymologically comes from -i- + -ty + -ate. Gravitate and levitate are related to gravity and levity through gravis and levis, which give Modern English the bound bases <Grave> and <Leve>. A new -itate suffix allows for newer words like gravitate and levitate to exist in the <Grave> and <Leve> word families.
Grave + i + ty → gravity
Grave + itate → gravitate
Leve + i + ty → levity
Leve + itate → levitate
The -itate suffix additionally occurs in the word sanitation, which is also a new word that developed in Modern English, first attested in 1848. Sanitation developed from sanitary + ate + ion. But *<Sanitary + ate + ion> would produce *sanitariation. The word sanitary is a modern borrowing from French sanitaire, which is itself a construction from Latin sānitās + aire. The -aire is the French form of English -ary. Latin sānitās comes from sānus + -tās. The Latin sānus gives English the free base <Sane>. Thus, both sanitary and sanitation, which developed in more contemporary Modern English, contain new suffixal constructions: -itary and -itate.
Sane → sane
in + Sane → insane
Sane + i + ty → sanity
Sane + itary → sanitary
Sane + itate + ion → sanitation
(The -itary suffix also occurs in the words dignitary and hereditary, which are newer words that arose in Modern English but have the Latin sources dignitās and hērēditās.)
As for words such as acidity, dignity, and infinity, the sequence of <i> followed by <t> is clearly not the -it(e) suffix. Instead, as previously explained, the modern -ty suffix, which forms an abstract noun denoting a quality or condition, comes from the Latin -tās. The -i- that precedes the -ty is a connecting vowel. Not every word that contains the -ty suffix also contains the -i- connecting vowel.
Ace + id + i + ty → acidity
Dign + i + ty → dignity
in + Fine + i + ty → infinity
Beau + ty → beauty
Du(e) + ty → duty
Royal + ty → royalty
Determining if a word contains the -it(e) suffix clearly requires an understanding of Latin as well as knowledge of the chronology of specific words. Many words contain the sequence of the graphemes <i> and <t>. However, only if a word comes from a Latin past participle with an -itus ending does the word contain the -it(e) suffix. More modern words that developed from BASEity contain modern suffixal constructions such as -itate and -itary. Finally, words that end in -ity contain the connecting vowel -i- followed by the -ty suffix from Latin -tās. Never automatically assume that <it> is any word is the -it(e) suffix. Always investigate the history of the specific word first.
