From Longman Dictionary of Contemporary Englishthe mainstay of somethingthe mainstay of somethinga) IMPORTANTan important part of something that makes it possible for it to work properly or continue to exist Agriculture is still the mainstay of the country’s economy. b) MAINsomeone who does most of the important work for a group or organization She was the mainstay of the team. → mainstay
Examples from the Corpus
the mainstay of something• Inflections, positions, and signpost words are the mainstay of syntax.• What we once regarded as the mainstay of our society has become the exception and not the rule.• Milk products typical of nomadic pastoralists formed the mainstay of their diet.• Newsome is the mainstay of our central defence and worth all your Ibrox millions and more.• In terms of the size of the contribution, then, it is the informal sector which is the mainstay of community care.• Middle class women, once the mainstay of all volunteer endeavors, are no longer an unlimited resource.• Agriculture was the mainstay of the community, although most other rural crafts had disappeared.• Cloth - mainly wool and linen - was the mainstay of this trade. 