IPA: /ɪnˈvɛktɪvnəs/
KK: /ɪnˈvɛktɪvnəs/
The quality of using harsh or insulting language; the tendency to criticize or attack someone verbally.
His invectiveness during the debate shocked many viewers.
Invectiveness is formed from "invect-" (from Latin "invectus", meaning to carry in or bring in) and "-iveness" (a suffix indicating a state or quality). The word refers to the quality of being invective, or characterized by harsh, critical language.
Think of 'bringing in' ('invect-') strong, critical words — that's what invectiveness means.