Guano
/ˈɡwɑːnəʊ/
Definition 1 of 1
Pro Tip 1/3Historical Value
Guano was a highly valued resource in the 19th century, almost as precious as gold. 
Historians often note the 'guano boom' that enriched Peru's economy.
Pro Tip 2/3Ecological Impact
Harvesting guano can disturb natural habitats, so its use is sometimes controversial. 
Environmentalists argue against guano extraction from delicate island ecosystems.
Pro Tip 3/3Slang Usage
In casual speech, 'guano' can refer to anything regarded as worthless or unimportant. 
His ideas were dismissed as guano by the other team members.