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1.
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
 
2.
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