secret is sekasus

sekasus = secret (noun) (Some things Google found for "sekasus": a rare to unusual term; user names; may possibly mean something untranslatable in Indonesian; similar sukses means success in Indonesian; 1905 telegraph cipher code for a specific number of boxes of a specific size of citrus fruit; similar Sekasua is the name of a place in Ghana)

Word derivation for "secret" :
Basque = sekretu, Finnish = salaisuus
Miresua = sekasus

This is a new word. The Basque word may be a borrowed word, or may be derived from Latin.

I found the word secret once in Alice's Adventures in Wonderland, it's in a verse read by the White Rabbit at the court of justice.

"Don't let him know she liked them best,
For this must ever be
A secret, kept from all the rest,
Between yourself and me."