What does "cufflink" mean?

A button or stud used to hold a sleeve cuff together.

Cufflink

Common synonyms include: cuff fastener, cufflink jewelry, double cuff fastener, dress cuff adornment, fashion cuff accessory, shirt cuff fastener.

/ˈkʌflɪŋk/ noun

noun ·Rare ·Advanced level

Noun

1
A button or stud used to hold a sleeve cuff together.
"Every gentleman needs at least one pair of cufflinks."
2
jewelry consisting of one of a pair of linked buttons used to fasten the cuffs of a shirt wordnet

"Every gentleman needs at least one pair of cufflinks."

From cuff + link.