Hi Andrey, For basic purposes, the answers above are correct: lunch is for mid-day, and dinner is in the evening. However, there are regional differences. Definitely in Northwest England (Eg. Leeds, Manchester, Liverpool) and Ireland, the word "dinner" sometimes refers to the mid-day meal (lunch). Perhaps because there it is often the largest meal of the day, and a smaller supper or tea - "tea" also referring to a meal, not the drink alone - follows in the evening. Note the definitions for "dinner" Richard has found: sometimes the usage is based on the size of the meal, not the time of day it is eaten. Yes, the locals get confused over this also. ;)

I checked two dictionaries, specifically Merriam-Webster Dictionary and Oxford lunch (probably short for luncheon) 1: a meal eaten in the middle of the day. 2: a usually light meal; especially : one taken in the middle of the day dinner 1a: the principal meal of the day 1b: a formal feast or banquet 1c: the main meal of the day, taken either around midday or in the evening. 1d: a formal evening meal. supper 1 a : the evening meal especially when dinner is taken at midday 1 b : a social affair featuring a supper; especially : an evening social especially for raising funds 1c: a light or informal evening meal. I find these definitions a little confusing. The words "lunch" and "dinner" both date back to the 1800's. The word "supper" (from French) dates back to the 1300's. Here in Canada we use lunch and dinner. But 50-75 years ago the word supper was used more often than dinner. I believe that most native English speakers would understand "supper" to mean "dinner", but they would most often use the word "dinner".