Exhibit Antiques has dated this piece to the 1800s.
A Georgian Irish glass decanter dating to c1815. Original radial target stopper with the applied neck rings with flute moulding to the lower section. Radial moulding to the underside. Probably Cork.

Date & Origin
Cork, Ireland, c1815. Period of George III.
Condition
Excellent, age-related wear as shown.
Dimensions
Height: 27cm (including stopper)
Diameter: 12cm.
Historical Context
Hand-blown around the time the Apothecaries (1815) Act prohibited unlicensed medical practitioners.
Relevant References
A similar example is featured in The Decanter Ancient to Modern by Andy McConnell on p180 plate 4.
Exhibit Antiques has dated this piece to the 1800s.
Specialists in 18th & 19th century antique glass
You can view the stock and full dealer information on the Exhibit Antiques Profile Page