The Oxford English Dictionary is best for finding the "Descriptive" meaning. This is the literal meaning, known also as denotative. It can also help you with figurative meanings, but it is not its primary purpose.
The correct answer is: etymological. This is because the OED traces and marks the historical development of the English Language. Therefore it is etymological. Hope this helps my friends!! :)
"Today nobody brought his or her instrument" is correct. It is common for people to use "their" in a sentence like this, but "his or her" is the more proper term.
