What does "misapprehension" mean?

A failure to understand something; an illusion, misconception or misunderstanding.

Misapprehension

Common synonyms include: misunderstanding, abuse of terms, catachresis, clerical error, contorting, corrigendum.

noun

noun ·5 syllables ·Uncommon ·Advanced level

Noun

1
A failure to understand something; an illusion, misconception or misunderstanding. countable, uncountable
"They had thought it obsolete, but, were relieved of this misapprehension by Yule’s friend Major Trotter."
2
an understanding of something that is not correct wordnet

"They had thought it obsolete, but, were relieved of this misapprehension by Yule’s friend Major Trotter."

From mis- + apprehension.