1. noun /tak,tæk/
a) A small nail with a flat head.
I thought that my refusing Barnard would alienate Botha, and decided that such a tack was too risky.
b) A small, sharp, nail-like object used especially to affix thin items to thicker ones, but not heavily used in carpentry.
Syn: coming about
2. verb /tak,tæk/
a) To nail with a tack (small nail with a flat head).
b) To sew/stich with a tack (loose seam used to temporarily fasten pieces of cloth).
See Also: tacky
Wikipedia foundation.