Abhidhānappadīpikā

The earliest Pali dictionary we possess — built on the lines of the Sanskrit Amarakośa: a dictionary of synonyms rather than an alphabetical one, 1,203 verses in three sections (celestial, terrestrial, miscellaneous), each divided again, with the last two divisions given to homonyms and to indeclinables.

Its author is a Moggallāna, but not the grammarian. The Gandhavaṃsa calls him Navamoggallāna, “new Moggallāna”, which is taken to distinguish him from the founder of the second school; the Pali catalogue is more specific still and calls him Cullamoggallāna. The work refers to Parakkamabāhu, which puts it in the late 1100s CE and makes the two Moggallānas roughly contemporary.

A caution worth carrying into any use of it: a proportion of its vocabulary was coined out of Sanskrit for the dictionary's own purposes, so a word's presence here is not evidence that any Pali text ever used it.