IPA: /ɪnˈkaʊʃəsnəs/
KK: /ɪnˈkɔːʃəsnəs/
The quality of not being careful or cautious, often leading to mistakes or accidents.
His incautiousness in handling the fragile items resulted in several breakages.
Incautiousness → It is formed from "in-" (meaning not) and "cautious" (from Latin "cautiosus", meaning careful) and the suffix "-ness" (meaning the state of being). The word describes the state of not being careful or lacking caution.
Think of 'not careful' ('in-' means not, and 'cautious' means careful) to remember that 'incautiousness' refers to a lack of caution.