It's possible that:
* It's a misspelling or variation of another word. There may be a similar-sounding word in Kikuyu that has a different meaning.
* It's a slang term or regional dialect. Some words might be used in specific areas or groups and not widely known.
* It's a newly coined word. Sometimes new words are created to express new concepts or ideas.
To get a clearer understanding, it would be helpful to know:
* The context in which you heard the word. This could give clues about its meaning.
* The speaker's background. If they are from a specific region or group, they might be using a local dialect.
If you can provide more information, I can help you find the meaning of "mambarita" or identify a similar-sounding word in Kikuyu.