availability

Concise Oxford English Dictionary © 2008 Oxford University Press:
available/əˈveɪləbl/

▶adjective

• 1 able to be used or obtained.

• 2 not otherwise occupied; free.

– derivatives
availability noun,
availableness noun.

– origin ME (in the senses ‘effectual, serviceable’ and ‘legally valid’): from avail + -able.