valiant
adj. C1 Advanced US //ˈvæɫjənt// UK //vˈælɪənt// valiant
adj. showing great courage or determination, especially in a very difficult situation. You use this to describe someone who tries very hard even if they might not win.
adj. possessing or showing courage or determination in the face of danger or difficulty. Often carries a connotation of noble effort despite likely failure.
The firefighters made a valiant effort to save the building.
Despite their valiant defense of the city, the outnumbered soldiers were eventually forced to retreat.
The explorer's valiant attempt to reach the summit alone became a legendary tale of human endurance, even though he was turned back by the storm just meters from the peak.
Usage
Typically used attributively before a noun like 'effort', 'attempt', or 'struggle'.