The Great Southern and Western Railway (GS&WR) was an Irish gauge railway company in Ireland from 1844 until 1924.
Haplogroup I-M253, also known as I1, is a Y chromosome haplogroup.
The Japanese submarine I-1 was a ''J1 type'' submarine built by Kawasaki, Kobe, for the Imperial Japanese Navy.
The LB&SCR I1 class was a class of 4-4-2 steam tank locomotives designed by D. E. Marsh for suburban passenger service on the London, Brighton and South Coast Railway.
The Motorola i1 is an Internet-enabled smartphone by Motorola, running the Android operating system designed by Google.
The Polikarpov I-1 was the first indigenous Soviet monoplane fighter.
In set theory, a branch of mathematics, a rank-into-rank is a large cardinal property defined by one of the following four axioms given in order of increasing consistency strength.