Substance – la sustancia
(Pronounced soos-tahn-thyah)
To remember that substance is pronounced soos-tahn-thyah (sustancia) in European Spanish, use the following mnemonic:
After using a strange chemical substance on him, he sues the tanning salon when the active (sustancia) ingredient turns him blue.
Sustancia is feminine, so it's la sustancia. Imagine a lady stepping in a weird substance.