Where does “fortificandus” come from?

fortificandus (Latin) comes from Latin fortificō, from Latin fortis, from Old Latin forctis, from Proto-Italic forktis, from Proto-Indo-European bʰerǵʰ- — to rise; high, lofty; hill, mountain.

Definitions

Ancestry of “fortificandus”, step by step

Step	Language	Word	Meaning
1	Latin	fortificō	to strengthen, fortify
2	Latin	fortis	strong, powerful; firm, resolute, steadfast,...
3	Old Latin	forctis	strong
4	Proto-Italic	forktis	strong, robust
5	Proto-Indo-European	bʰerǵʰ-	to rise; high, lofty; hill, mountain

Every word from Proto-Indo-European bʰerǵʰ- →Every word from Proto-Italic forktis →Every word from Old Latin forctis →