1. To strengthen and make more rigorous defensive strategies, tactics, or positions, typically in military, sports, or security contexts
The team decided to tighten defense after conceding three goals in the first half.
O time decidiu apertar a defesa após sofrer três gols no primeiro tempo.
2. To increase vigilance and reduce vulnerabilities in protective measures
The government announced plans to tighten defense spending and military operations.
O governo anunciou planos para apertar a defesa e reforçar as operações militares.