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pronunciation: ther-mop-o-lee
function: adj.

To be outnumbered but remain fighting strong.

Often is used in conjunction with "fucking".
That shit was fucking Thermopylae.
by The_Anonymous August 19, 2008
A battle in which approximately 1000 (300 Spartan, 700 Thespian) Greek soldiers made a three day stand against a Persian force of 100,000 or so (estimates vary dramatically). They inflicted massive casualties on the Persians before being killed.
Thermopylae is the definition of badass.
by ugg2 March 20, 2007