An acid hydrolase (lysosomal acid lipase) is an enzyme that works best at acidic pHs. It is commonly located in lysosomes, which are acidic on the inside. Acid hydrolases may be nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases and phospholipases and make up the approximately 50 degradative enzymes of the lysosome that break apart biological matter.
References
Acid hydrolase Wikipedia(Text) CC BY-SA