IPA: /ˌɪnəˈfɛnsɪvnəs/
KK: /ɪnəˈfɛnsɪvnəs/
The quality of not causing harm or offense to others; being polite or gentle in behavior or speech.
Her inoffensiveness made her a favorite among her colleagues.
Inoffensiveness → It is formed from "in-" (meaning not), "offens" (from Latin "offendere", meaning to strike against or cause harm), and "-ness" (meaning the state or quality of). The word describes the state of not causing offense or harm.
Think of 'not' ('in-') causing harm ('offendere') — that's why inoffensiveness means the quality of being harmless.