Submarine/ˌsʌbməˈriːn/ Definition 1 of 3Pro Tip 1/3Military Context Used often in military settings to discuss naval capabilities or warfare strategy. The admiral briefed about their submarine fleet's readiness. Pro Tip 2/3Stealth Operations Submarines are associated with stealth and secrecy in operations beneath the sea. The submarine carried out a covert surveillance mission. Pro Tip 3/3Types and Capabilities Be aware of different types like 'nuclear' which suggest power source, or 'attack' for purpose. The nuclear submarine can remain submerged for months.