ˌprimary ˈstress BrE AmE noun [uncountable and countable]
technical the strongest force that is put on a part of a long word when you say it, like the force given to ‘pri’ in ‘primary’. It is shown in this dictionary by the mark ( ' ).
PRIMARY STRESS
Meaning of PRIMARY STRESS in English
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012