|1.||[ [Undefined_variable] ] determiner, one or the other indifferently|
|2.||[ adverb ] after a negative statement used as an intensive meaning something like `likewise' or `also'|
"he isn't stupid, but he isn't exactly a genius either" "I don't know either" "if you don't order dessert I won't either"
|3.||[ conjunction ] conjunction, alternative|
"Either your sister or your friend has been in the garden."