strengthening

(noun) becoming stronger.

(noun) the act of increasing the strength of something.

(verb) make strong or stronger. Synonyms: strengthen, beef up, fortify. Examples: "This exercise will strengthen your upper body." "Strengthen the relations between the two countries."

(verb) gain strength. Synonyms: strengthen. Example: "His body strengthened."

(verb) give a healthy elasticity to. Synonyms: tone, tone up, strengthen. Example: "Let's tone our muscles."