Tiffin is lunch, or any light meal. It originated in British India, and is today found primarily in Indian English. The word originated when Indian custom superseded the British practice of an afternoon dinner, leading to a new word for the afternoon meal. It is derived from the obsolete English slang tiffing, for "taking a little drink or sip". When used for "lunch"; it is not necessarily a light meal. Notably, it is used in the name of MTR, Mavalli Tiffin Room.
In South India and in Nepal, the term is generally used for between-meals snacks: dosas, idlis, etc. Outside South India, like Mumbai, the word mostly refers to any packed lunch, often light lunches prepared for working Indian men by their wives after they have left for work, or for school children by their parents. It is often forwarded to them by dabbawalas, sometimes known as tiffin wallahs, who use a complex system to get thousands of tiffin-boxes to their destinations. Tiffin often consists of rice, dal, curry, vegetables, chapathis or "spicy meats". In addition, the lunch boxes are themselves called tiffin carriers, tiffin-boxes or sometimes tiffins. South Indian Recipes provides you with some delicious tiffin recipes in the region.