Real Dictionary

glass ceiling
When people refer to a glass ceiling, they are talking about the attitudes and traditions in a society that prevent women from rising to the top jobs.

glass ceiling in American English
an unofficial policy regarded as being imposed on women and minorities that prevents them from advancing to higher positions in business, government, etc.
noun: an upper limit to professional advancement, esp. as imposed upon women, that is not readily perceived or openly acknowledged

glass ceiling in British English
noun: a situation in which progress, esp promotion, appears to be possible but restrictions or discrimination create a barrier that prevents it