It is a verb. It describes the action of making stronger.
Strengthens is a verb. It is the present tense, third person singular of the verb to strengthen.
part of speech
Adjective
What part of speech is thaw
The part of speech for oscillate is verb.
An adjective is a part of speech.
The Pumgo mainly strengthens your calf muscle.
Fluoride strengthens the enamel.
The part of speech for "answer" is a noun.
part of speech
The part of speech for this particular word is a noun.
adverb
what part of speech is work
what part of speech is beneath
The part of speech for "indefinite" is an adjective.
The part of speech for "buried" is a verb.
The part of speech for "rapid" is an adjective.
The part of speech for "twirl" is a verb.