E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
stands for 300. Scit B. trecentum sibi cogntum retinre. And,
again, Et B. trecentum per se retinere videtur. But with a line
above, it denotes 3,000. For Becarre and Bemol (French for B
sharp and B flat), see BECARRE. Marked with a B (French), i.e. a
poor thing. In the French language almost all personal defects
begin with the letter B; e.g. bigle (squint-eyed), borgne (one-
eyed), bossu (humpty), boiteux (lame), etc. Not to know B from a
battledoor. To be quite illiterate, not to know even his
letters. Miege tells us that hornbooks used to be called
battledoors. The phrase might therefore originally mean not to
know the B of, from, or out of, your hornbook. But its more
general meaning is not able to distinguish one letter from
another. He knoweth not a B from a battledoore.Howell; English
Proverbs. Distinguish a B from a battledore.Dekker: Guls
Hornebook. I know B from a Bulls foot. Similar to the proverb, I
know a hawk from a hernshaw. (See HA