Answer:
He doesn't consider Sissy is a proper name, as it may sound offensive.
Explanation:
“Sissy is not a name,” said Mr. Gradgrind.
The nickname Sissy is inappropriate in the English language as may be degrading for a person having this nickname. Allegorical, 'sissy' would be a person regarded as effeminate or cowardly.
But, the real meaning behind 'sissy' refers to the oldest daughter in the family, and it is short for Cecilia.
