From Longman Dictionary of Contemporary Englishlaw firmˈlaw firm noun [countable] SCLa company that provides legal services and employs many lawyers
Examples from the Corpus
law firm• Law firm were law firms, and areas such as marketing and finance were foreign to them.• After that, Feingold joined a Madison law firm and practiced civil litigation, including First Amendment law.• There is no private law firm where the defeated candidates can retire.• Fletchers was advised by Sheffield law firm Ashton Morton Slack. 