WordNet sense 1 (1/60 of a minute; the basic unit of time adopted under the Systeme International d'Unites):

s, second

WordNet sense 2 (ratio of the hypotenuse to the adjacent side of a right-angled triangle):

secant

WordNet sense 3 (an independent federal agency that oversees the exchange of securities to protect investors):

Securities and Exchange Commission

WordNet sense 4 ((of champagne) moderately dry):

unsweet

WordNet sense 5 ((of liquor) having a low residual sugar content because of decomposition of sugar during fermentation):

dry