out
1.
to make a hole in sth by removing part of it :
Hollow out the cake and fill it with cream.
2.
to form sth by making a hole in sth else :
The cave has been hollowed out of the mountainside.
out
1.
to make a hole in sth by removing part of it :
Hollow out the cake and fill it with cream.
2.
to form sth by making a hole in sth else :
The cave has been hollowed out of the mountainside.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005