Master/bachelor is the noun - the person. Master's/bachelor's is the possessive form. Masters/bachelors is the plural form of the noun. (Masters (degree) is also a level of higher education.) Examples: Noun: "My master is very harsh on me." "He is a bachelor because he is not married." Possessive form: "My master's house is always kept clean." "A bachelor's pad is typically quite small and very untidy." Plural noun: "They are masters of the skateboard - they skate really well!" "Lots of older bachelors join dating websites." I hope this helps!

Usually, you use the apostrophe: I earned a bachelor's degree in 1959. (I am a very old man.) I did not have the time or money to study for a master's degree. ***** In conversation, you do not need to include "degree": I have only a bachelor's. So I could not get any jobs that required a master's.