Where does “cantitandus” come from?

cantitandus (Latin) comes from Latin cantito, from Latin -ito, from Latin -tō, from Latin -tus, from Proto-Italic -tus, from Proto-Indo-European -tus — Derives action nouns from verb roots.

Definitions

Ancestry of “cantitandus”, step by step

Step	Language	Word	Meaning
1	Latin	cantito	I sing often or repeatedly
2	Latin	-ito	Forms frequentative verbs from existing verbs or...
3	Latin	-tō	Forms here
4	Latin	-tus	Forms the past participle of verbs; Forms...
5	Proto-Italic	-tus	—
6	Proto-Indo-European	-tus	Derives action nouns from verb roots

Every word from Proto-Indo-European -tus →Every word from Latin -tus →Every word from Latin -tō →