Where does “amarissimo” come from?

amarissimo (Italian) comes from Italian amaro, from Latin amārus, from Proto-Indo-European h₂eh₃mós, from Proto-Indo-European h₂eh₃- — to be hot; to burn.

Ancestry of “amarissimo”, step by step

Step	Language	Word	Meaning
1	Italian	amaro	bitter; bitter, bitterness; any of several herbal...
2	Latin	amārus	bitter (taste)
3	Proto-Indo-European	h₂eh₃mós	raw; uncooked; bitter
4	Proto-Indo-European	h₂eh₃-	to be hot; to burn

Every word from Proto-Indo-European h₂eh₃- →Every word from Proto-Indo-European h₂eh₃mós →Every word from Latin amārus →