1 (grow weaker) [+person, muscle, structure, economy] debilitarse; [+power, influence, resolve] menguarse; debilitarse without oxygen, the heart muscle weakens
the pound weakened against the dollar today hoy la libra ha bajado frente al dólar
prices have weakened las cotizaciones se han debilitado the Australian dollar weakened because of a cut in interest rates /I felt my resolve weakening/ as I surveyed the menu his influence is weakening when pupils sense a teacher's authority weakening, things can get out of hand with every day that passed she weakened the building's structure had weakened as a result of the tremor family structures are weakening and breaking up his voice had weakened since I last went to visit him I consider that the company has weakened as a result of stiffer competition
2 (give way) flaquear then something inside him said, "Don't weaken!" Jenny weakened and finally relented
we must not weaken now no debemos flaquear, ahora menos que nunca