Where does “gellad” come from?

gellad (Old Irish) comes from Old Irish gellaid, from Old Irish -aid, from Proto-Celtic -āti, from Proto-Indo-European -h₂ti — Forms factitive verbs from adjective stems.

Ancestry of “gellad”, step by step

StepLanguageWordMeaning
1Old Irishgellaidpledges oneself, vows, promises; pledges, gives...
2Old Irish-aidforms [[AP:Old Irish class A I present verbs
3Proto-Celtic-ātiForms verbs from nouns and adjectives
4Proto-Indo-European-h₂tiForms factitive verbs from adjective stems
Every word from Proto-Indo-European -h₂ti →Every word from Old Irish -aid →Every word from Proto-Celtic -āti →