What does ply stand for?

Plywood (VRA)

Plymouth - Record label

Bolyu - Language code (ETLW)

Photolimited Yield

Photoluminescence Yield - Spectroscopy

Plymouth - NCIC firearms make code (NCIC)

Plywood

Polaris Energy - Vancouver Stock Exchange symbol

Politically - Telegraphy (PCTE)

Polyphase Corp. - AMEX symbol (SPSG)

Prune Extract Lactose Yeast Medium - Microbiology