A "loss" is a slang term for a loss in the trader community, derived from the English word loss. The expression caught on among Russian-speaking traders because the Russian word for "elk" (los) sounds like "loss": big losses on an exchange are jokingly described as the trader having "caught an elk". Despite the ironic tone, the term denotes a perfectly serious concept — recording a negative result on a trade.

Most often a loss refers to closing a position with a loss of capital, for example when the asset's price moved against the trader's expectations. A separate case is the triggering of a stop-loss — a protective order that automatically closes a position when a predetermined loss level is reached. In this case the trader is said to have been "stopped out".

The occurrence of losses is a natural part of trading, and it is impossible to avoid them entirely. A professional approach consists not in denying losses but in managing risk: limiting position size, using stop orders and maintaining discipline. That is why competent market participants treat the recording of a small loss as a normal working tool rather than a catastrophe.