There is no specific symbol to represent brother in Gaelic or in Celtic symbolism. Celtic symbols are sometimes wrongly attributed to specific meanings for commercial benefit.
In written form, the Irish Gaelic word for brother is ''deartháir'' and the Scots Gaelic word is ''bràthair.'' The ancient written form for the Irish Gaelic language and for the Welsh language is called ''Ogham.'' Ogham letters consist of vertical lines with horizontal strokes and notches on them. Words read from bottom to top along the vertical line. Examples of this ancient script can be found by searching for images of ''Ogham letters'' in any Internet browser.