Master Degree/Masters/Master's Degree
'Masters' is the plural of 'master' meaning a boss, someone in control, leader, skilled person, original copy etc. It has nothing to do with 'academic pursuit'.
Master's Degree refers to an academic degree, usually awarded after one or two years of postgraduate study. There is nothing like 'master degree'. It is also wrong to refer to a 'Master's degree' as just 'masters'.
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