briar: There are two distinct words briar in English, both of which can also be spelled brier, and as their meanings are fairly similar, they are often confused. The older [OE] is a name given to the wild rose, although in fact this usage is as recent as the 16th century, and in Old English times the word was used generally for any prickly bush, including particularly the bramble.
The Old English form was brēr, but it is not known where this came from. The other briar, ‘wild heather’ [19], is the one whose root is used for making briar pipes. The word comes from French bruyère, and was spelled bruyer when first introduced into English in the third quarter of the 19th century; the current spelling is due to assimilation to the other briar.
The French form comes from Gallo-Roman *brūcaria, a derivative of *brūcus, which was borrowed from Gaulish brūko. It appears to be related to the Greek word for ‘heather’, ereikē, from which English gets the technical botanical term ericaceous [19].