Synonyms for X (same or very similar meaning)
WordNet sense 1 (the cardinal number that is the sum of nine and one; the base of the decimal system):
decade, ten, tenner
WordNet sense 2 (the 24th letter of the Roman alphabet):
ex, letter x
WordNet sense 3 (street names for methylenedioxymethamphetamine):
ecstasy, go, Adam, cristal, XTC, disco biscuit, hug drug
WordNet sense 4 (being or denoting a numerical quantity but not order):
cardinal
From the ODE community, based on WordNet
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