défaillons
The term "défaillons" is the first-person plural present indicative form of the French verb "défaillir". "Défaillir" generally means to fail, to weaken, to falter, or to swoon. Therefore, "défaillons" translates to "we fail," "we weaken," "we falter," or "we swoon." The specific nuance depends heavily on the context in which it is used.
In a physical sense, "nous défaillons" might describe a group experiencing exhaustion or a loss of strength,