Wiktionary
n. An ornamented pin used to secure a necktie's end flat against the shirt, a stickpin.
WordNet
Usage examples of "tie tack".
Maude had given him the tie tack Christabel had bought for him, and he'd kept it with him the whole time she was in the hospital.
No wallet, no identity papers, not a banknote, key chain, or tie tack.
He was wearing an impeccably cut tropical-weight chalk-stripe suit, pure white Turnbull and Asser shirt with a regimental tie, gold nugget cuff links and tie tack, polished oxblood wingtip shoes.
Above his soft, expansive belly, a silver tie tack anchored a shiny claret necktie to his cheap white shirt.
Parkins Gillespie arrived first, wearing a green tie set off by a VFW tie tack.
He adjusted the black tie so that it covered the bullet holes, keeping it in place with the Nazi Party pin that the agent had used as a tie tack.
Against the fabric of the black shirt was a light gray necktie with a golden lion's head for a tie tack.
His tie was cinched tightly at his neck and tacked down with a gold tie tack.
A silver tie tack with a sapphire in its head pierced the white at his throat.
The shirt was white and held in place with a dove grey tie, complete with a silver tie tack.