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to become weak; to decline; to wear; to abate; to decay; to wither; to waste away
年齢を重ねるとともに体力が衰えてきました。
My physical strength has weakened with age.
長い入院で体力が大幅に衰えた。
His physical strength declined greatly after a long hospital stay.
祖父は高齢になり足腰が衰えている。
My grandfather's legs have been weakening as he ages.