Longman Dictionary of Contemporary English - branch

~1 n 1 »ON A TREE« a part of a tree that grows outwards from the trunk (=stem) and that has leaves, fruit, or smaller branches growing from it  (a fallen tree trunk) 2 »IN A LOCAL AREA« a shop, office etc in a particular area that is part of a large company  (The bank has branches all over the country. | a branch office in Boston) 3 »OF AN ORGANIZATION« a part of a government or other organization that deals with one particular part of its work  (All branches of government are having to cut costs.) 4 »OF A SUBJECT« one part of a large subject of study or knowledge + of  (Newton developed a branch of mathematics called calculus.) 5 »OF A FAMILY« a group of members of a family who all have the same grandparents or ancestors  (the wealthy South American branch of the family) 6 »SMALLER PART« a smaller less important part of something that leads away from the larger more important part of it  (a branch of the river Arno) ~2 v to divide into two or more smaller, narrower, or less important parts  (branch into two)  (When you reach Germain Street, the road branches into two.) branch off ~ phr v 1 if a road, passage, railway etc branches off from another road etc, it separates from it and goes in a different direction + from  (a passage branching off from the main tunnel) 2 to leave a main road + from/into  (We branched off from the main road and turned down a country lane.) 3 to start talking about something different from what you were talking about before + into  (Then the conversation branched off into a discussion about movies.) branch out ~ phr v to do something different from what you usually do  (Don't be afraid to branch out and try new ideas. | branch out into (doing) sth)  (Profits were falling until the bookstore branched out into selling CDs and cassettes.)