leaving 'e'

[googl]

Dear teachers,

is there any rule there? why 'e' is omitted when adding suffix?

actor + ess -> actress
waiter + ess -> waitress
enter + ance -> entrance
enter + y -> entry

but emperor + ess -> empress. When should I omit 'e' (or 'o')?

[Alan]

It's normally omitted, but there is no 'rule' as such. Simply learn each form as you go!

[googl]

Are there any other letters which are omitted in this way too? If yes, could You name some? (is it only with 'o' and 'e'?)

[Alan]

'E' is the only letter that is commonly omitted in compounds or extensions. Others may be from time to time.