For example, Scottish Gaelic loisg "to burn" goes back to *l̥h₂p-sḱé-, a sḱe-present of the root *leh₂p- which is also the source of Ancient Greek λάμπειν (lámpein) "to shine" via its nasal present *l̥h₂⟨n⟩p-.
The authors of the Lexikon der indogermanischen Verben proposed that they were derived from a number of prior grammatical aspects with distinct (but lost) meanings.
[10][11] The phenomenon of nasal-infixing as inherited from Proto-Indo-European is found in Sanskrit with the greatest morphological transparency, and is taken as a guide to examining the feature in kindred languages.
The behaviour[a] of the class-7 root √yuj-[b] class-5 √śru-[c] and class-9 krī-[d] can be seen thus:[12][14] While these were seen as 3 separate classes by the ancient Sanskrit grammarians, Ferdinand Saussure demonstrated, as part of his landmark work in postulating the Laryngeal theory, that these were slightly different manifestations of the same nasal infix.
In J. R. R. Tolkien's constructed languages Quenya and Sindarin spoken by the Elves, the nasal infix forms the past tense of many verbs.
These are most clear in Quenya which shows the nasal infix in the past-tense forms ending in any consonant besides -m, -n, or -r. Thus, cen- "to see" has the past tense cen-në, but mat- "to eat" has not *mat-në but the metathesised ma(n)t-ë.