Where does “Gillham” come from?

Gillham (English) comes from English William, from Anglo-Norman Willame, from Old High German Willahelm, from Old High German helm, from Proto-West Germanic helm, from Proto-Germanic helmaz, from Proto-Germanic halmaz, from Proto-Indo-European ḱolh₂mos — to pierce, strike; to stick; prick; stab.

Ancestry of “Gillham”, step by step

StepLanguageWordMeaning
1EnglishWilliamradiotelephony clear-code word for the letter W
2Anglo-NormanWillame
3Old High GermanWillahelmWilliam
4Old High Germanhelmhelmet
5Proto-West Germanichelmhelmet
6Proto-Germanichelmazhelmet
7Proto-Germanichalmazhalm; stem; stalk; straw; hay
8Proto-Indo-Europeanḱolh₂mosstalk
9Proto-Indo-Europeanḱelh₂-to pierce, strike; to stick; prick; stab
Every word from Proto-Indo-European ḱelh₂-