1. Plural of nifty; things that are clever, useful, or impressive in a small way.
Usage: informal; often used to refer to clever gadgets, tricks, or useful items
2. The 1950s (from the decade's nickname 'the nifties').
Usage: informal; dated; chiefly British

Examples

• She showed me some nifties she'd picked up at the hardware store.
• That app has some really useful nifties built into it.
• He collected all sorts of mechanical nifties from the 1950s.
• The software includes several nifties that make editing easier.
• My grandfather loved the music and fashion of the nifties.