2. Initialism. (US Navy) Sub Surface Nuclear - nuclear powered attack submarine ¹
¹ Source: wiktionary.com
Lexicographical Neighbors of SSN
SSEES SSG SSGN SSGNs SSGs SSH SSHRC SSI SSIA SSID | SSK SSKs SSL SSM SSMs SSN (current term) SSNRI SSNs SSO SSP | SSP31 protein kinase SSPE SSPX SSPs SSR SSRI SSRIB SSRN SSS SSSI |