There are several expansions of the abbreviation ISL:

• Formally, ISL can refer to International Sign Language, aka Gestuno.
• Informally, ISL can refer to Irish Sign Language.
• More formally, ISL is the SIL code for Israeli Sign Language.
• ISL is the NATO country code for Iceland.
• In mathematics, i.s.L. can stand for in the sense of Lyapunov.
• In reference to a Storage Area Network, and switched networks ISL stands for Inter Switch Link.
• ISL may also stand for the proprietary Cisco Inter-Switch Link protocol.
• ISL can refer to the Independent School League, most commonly a group of 16 New England preparatory schools.
• ISL can refer to the Independent School League, a group of 17 Washington, DC-area preparatory schools.
• ISL can refer to the Independent School League, a group of 9 Illinois preparatory schools.
• ISL was an initialism for the British based Ice Hockey Superleague (1996–2003)
• ISL can refer to the security firm Intercon Security

ISL | ISL