bowstring
From LSJ
μούνη γὰρ ἄγειν οὐκέτι σωκῶ λύπης ἀντίρροπον ἄχθος → I have no longer strength to bear alone the burden of grief that weighs me down, I no longer have the strength to hold up alone the weight of grief that pushes against me, I no longer have the strength to counterbalance alone the weight of grief that acts as counterweight, I have no longer strength to balance alone the counterpoising weight of sorrow
