A second language (a language being learned, as opposed to mother tongue).

(astrophysics) second Lagrange point, located further out from the primary of a system where a smaller object orbits a larger one, behind the smaller object, inline with a line drawn through the centres of the larger and smaller objects

(computing) The second-level cache of a processor, farther away from the processor than the first level cache. / (networking) The data link layer in the seven layer OSI network model.

(Internet, derogatory) Initialism of learn to play. Used in Internet games as a slur against weak or inexperienced players.

layer two tunnelling protocol