Plain-English definition
When you trade in shallow liquidity, your order eats through the available depth and finishes at a worse price than the screen quoted. That gap is slippage, and it is the tax shallow water charges.
It is why depth matters more than the quoted price for anyone moving real size. A great price you cannot actually fill is not a great price.
Why it matters
Slippage matters because crypto markets can look precise while still being shallow, crowded, or poorly sourced. A useful read is not just the number. It is the number, the size behind it, the context around it, and the part it cannot explain.
Simple example
A simple Slippage example is a reader comparing two venues with the same headline price but different depth. The deeper venue can absorb more capital before the trade, peg, or yield reading starts to move against the user.
How Bathymark uses this term
Bathymark uses Slippage to translate open market data into live liquidity readings. When the term touches a live page, the reading links back to the relevant chain, protocol, stablecoin, DEX, perps, or Signal so the source remains checkable.
Common mistake
The common mistake is treating Slippage as a complete signal by itself. Bathymark treats it as one instrument: useful when read beside liquidity, source, size, and what the number cannot prove.