Where does “kern” come from?

kern (Manx) comes from Middle Irish ceithern, from Old Irish ceithern, from Latin quaterniō, from Latin quaternī, from Latin quaternus, from Latin quater, from Latin quattŭor, from Portuguese quarto — and.

kern (Manx): soldier, infantryman, yeoman; pawn

Definitions

soldier, infantryman, yeoman; pawn

Ancestry of “kern”, step by step

Step	Language	Word	Meaning
1	Middle Irish	ceithern	A band or troop of soldiers or fighting men, kern
2	Old Irish	ceithern	band of soldiers
3	Latin	quaterniō	The number four (e.g. on a dice)
4	Latin	quaternī	—
5	Latin	quaternus	four each; four at a time
6	Latin	quater	four times
7	Latin	quattŭor	four; 4
8	Portuguese	quarto	ordinal form of quatro; fourth; quarter; fourth;...
9	Old Portuguese	quarto	quarter
10	Latin	quārtus	fourth
11	Proto-Indo-European	kʷeturtos	—
12	Proto-Indo-European	kʷetwóres	four
13	Proto-Indo-European	kʷe-	and

Every word from Proto-Indo-European kʷe- →Every word from Proto-Indo-European kʷetwóres →Every word from Proto-Indo-European kʷeturtos →