I recall the surprise I felt back in the 1980s when, in a new edition of a high school literature book, I came across a footnoted reference to Cain and Abel. My surprise came from the fact that the editors had felt that the targeted generation of American children could have reached high school age without having heard about Cain and Abel, that a footnote to identify them was necessary.
This week I was reading up on holly and came across this sentence:
‘Nellie R. Stevens’ holly typically reaches a height of about 30′, spreads out about 15′ at its base and has a pyramidal shape (i.e., it’s narrower at the top).
This time I was surprised that the writer felt it necessary to explain the meaning of “pyramidal.”
I doubt that the writer was trying to be considerate to readers for whom English is a second language. For one thing, the word pyramid is very similar from one Indo-European language to another. And even speakers of non-Indo-European languages who are educated enough to be reading about plants in English will surely have heard of the Great Pyramid in Egypt.
I think that the explanation that something “pyramidal in shape” is “narrower at the top” could be a symptom of something very disturbing: a knee-jerk assumption that the average reader has a less than average command of vocabulary.