IPA: /ɪnˈsɪkjərnəs/
KK: /ɪnˈsɪkjərnəs/
A state of being uncertain or anxious about oneself or one's abilities.
Her insecureness made it difficult for her to speak in front of large groups.
Insecureness → It is formed from "in-" (meaning not) and "secure" (from Latin "securus", meaning free from care or safe) and the suffix "-ness" (meaning the state of being). The word "insecureness" refers to the state of being not secure or lacking safety.
Think of 'not' ('in-') being added to 'safe' ('secure') to describe a state of feeling unsafe or unprotected.