sun‧bathe /ˈsʌnbeɪð/
verb [intransitive] to sit or lie outside in the sun, especially in order to become brown:
Her mother was sunbathing in the back garden.► There is no noun ‘sunbath’:
Let’s go and sunbathe/do some sunbathing (NOT have a sunbath). [TahlilGaran] Dictionary of Contemporary English ▲