IPA: /ɪnˈdiːsəntli/
KK: /ɪnˈdisəntli/
In a way that is considered improper or offensive, often relating to behavior or appearance.
He spoke indecently about the situation, making everyone uncomfortable.
Indecently → It is formed from "in-" (meaning not) and "decens" (from Latin, meaning proper or decent) and the suffix "-ly" (meaning in a manner). The word "indecently" means in a manner that is not proper or decent.
Think of 'not' ('in-') being combined with 'proper' ('decens') to remember that 'indecently' means behaving in a way that is not proper.