What are the Adjectives of word weaken?

The word "weaken" is a verb, not an adjective. It describes an action, not a quality.

Here are some adjectives that relate to the concept of "weaken":

Describing something that is weak:

* Weak

* Feeble

* Fragile

* Delicate

* Frail

* Tenuous

* Paltry

* Unstable

* Insecure

* Flimsy

Describing the act of weakening:

* Weakening

* Eroding

* Diminishing

* Debilitating

* Enervating

* Sap

Describing something that causes weakness:

* Enervating

* Debilitating

* Exhaustive

* Draining

* Destructive

* Damaging

The best choice of adjective will depend on the specific context in which you want to use it.