Sniper
Also: sniper bot, sniping
A sniper is a bot that watches the network and buys a new token the instant it is created or liquidity is added, often in the same block. Snipers pay high priority fees to be first and usually sell quickly once ordinary buyers show up.
Two things matter for a reader. First, if you buy in the first minutes, you are trading against bots that already have a price advantage. Second, some “snipers” are the token's own creator, buying a large share of supply from many wallets this way. A large sniper share of supply means a risk of heavy selling once the price rises.