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Synonyms for Alternative (same or very similar meaning)

WordNet sense 1 (one of a number of things from which only one can be chosen):
choice, option

WordNet sense 2 (allowing a choice):
alternate, alternate

WordNet sense 3 (being of second rank or importance or value; not direct or immediate):

WordNet sense 4 (not conventional or conformist):

WordNet sense 5 (necessitating a choice between mutually exclusive possibilities):
mutually exclusive

WordNet sense 6 (serving or tending to divide or separate):

From the ODE community, based on WordNetadd/edit