understrength

[ uhn-der-strengkth, -strength, -strenth ]
/ ˌʌn dərˈstrɛŋkθ, -ˈstrɛŋθ, -ˈstrɛnθ /

adjective

having insufficient organizational strength; lacking in personnel: an understrength army.
insufficient in power or efficacy.

Origin of understrength

First recorded in 1920–25; under- + strength