What is the synonyms word of febble?

"Febble" is not a recognized word in standard English. It's likely a misspelling of "feeble."

Here are some synonyms for feeble:

* Weak

* Frail

* Infirm

* Paltry

* Insignificant

* Unimpressive

* Dim (in the sense of light or sound)

* Weak-willed (for personality)

Please clarify if you meant a different word.