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Webster 1913 Edition
Bo
Bo
,int
erj.
 [Cf. W. 
bw
, an interj. of threatening or frightening; n., terror, fear, dread.] An exclamation used to startle or frighten. 
[Spelt also 
boh 
and boo
.] Webster 1828 Edition
Bo
BO
, exclam. A word of terror; a customary sound uttered by children to frighten their fellows.Definition 2025
bő
bő
See also: Appendix:Variations of "bo"