the.com/sportsbook

means A sportsbook is a business (physical counter or app) that takes bets on sports outcomes and sets the odds so it profits regardless of who wins.

from A straightforward compound: 'sports' plus 'book,' from the old gambling sense of 'book' as a bound ledger where bookmakers recorded wagers and odds — hence 'bookmaker,' shortened to 'bookie.' The word simply names the literal record-keeping of bets, now digitized but still carrying the ledger in its name.