IPA: /klænˈdɛstɪnli/
KK: /klænˈdɛstɪnli/
In a way that is secret and not meant to be known by others.
They clandestinely met to discuss their plans without anyone noticing.
Clandestinely → It is formed from "clandestinus" (meaning secret or hidden) and the suffix "-ly" (meaning in a manner). The word "clandestinely" means in a secret or hidden manner.
Think of something done in a 'secret' way ('clandestinus') — that's why 'clandestinely' means to do something secretly.
No commonly confused words.