atenololPronunciation: /əˈtɛnəlɒl/Definition of atenolol noun [mass noun] Medicine a beta blocker used mainly to treat angina and high blood pressure. Origin: 1970s: perhaps from a(ngina) + ten(sion) + (propran)olol, a related compoundatenolol in other Oxford dictionaries Definition of atenolol in the US English dictionary