Bád (baud), a boat.
Badhun (bawn), a cow fortress, the bawn of a castle.
Baile (bally), a town, a townland; bally, balli, vally and in the eastern counties bal.
Bán (bawn), white or fair coloured; bane, baun, bawn, vane, vaun.
Barr (baur), the top, the highest point; bar, baur. The Bar of a townland (used in the north) is the high or hilly part.
Beag (beg), little.
Bealach (ballagh), a road or pass; ballagh, vally.
Bealltalne (beltany), the first day of May; celebrated as a festival by the pagan lrish.
Beann (ban, ben), a horn, a gable, a peak, or pointed hill.
Beannchar (banaher), horns, gables, peaks; banagher, bangor.
Bearn, bearn, bearnas (barn, barna, barnas), a gap, a gap in a mountain; barna, barny, varna, varny, barnis, varnis, and often in the north barnet.
Bearnach (barnagh), gapped.
Beith (beh), the birch tree; beitheach (behagh) a birchy place; behy, beha, beagh, behagh, veha, vehy etc.
Bél, beul (bale), the mouth, an entrance, a ford; often joined to ath in the compound bél-atha (bellaha, bella), a ford-mouth or ford entrance.
Bile (billa), a large ancient tree; a tree held in veneration for any reason; billa, billy, villa, ville, villy, bella, vella.
Biorar (birrer), watercress; usually corrupted to biolar (biller); viller, vilra.
Bo, a cow; bo boe, and by eclipse, moe (mbo).
Boireann (burren), a large rock, a rocky district.
Both (boh), a tent or hut; bo, boha, bohy, voe.
Bóhar (boher), a road; boher and voher. In some of the eastern counties it is corrupted to batter. Bohereen a little road.
Braghad (braud), the throat; a gorge: braid, broad, braud.
Bran, a raven.
Breach (breagh), a wolf; occurs in the compound breach-mhagh (breaghvah), wolf-field.
Bri (bree), a hill; breebray.
Broc (bruck), a badger; brock, brick, and, by eclipse, mrock.
Brocach (bruckagh), a badger warren; brockagh, brocky.
Brugh (bru), a palace; a distinguished residence; bru, bruff. Bruighean (breann) has the same meaning, but in modern times it is used to denote a fairy palace; breen, bryan, breena, vreena.
Buaile (boolia), a booley, a feeding or milking place for cows; booley, boley, boola , voola, voula, vooly.
Buidhe (bwee or boy), yellow; boy, wee, &c.
Buirghes (burris), a burgage or borough; borris and burris.
Bun the end or bottom of anything; the mouth of a river.

From the Appletree Press title: A Dictionary of Irish Place Names.
Also from Appletree: Book of Irish Names.