Anonymous

life span is less commonly used https://www.macmillandictionary.com/spel... https://dictionary.cambridge.org/spellch... https://dictionary.cambridge.org/diction...

Anonymous

life span (also lifespan) https://en.oxforddictionaries.com/defini...

Anonymous

It makes no difference but the normal way of typing the word is 'lifespan' without the space.

Anonymous

Life span

Anonymous

lifespan or life-span It's a compound-noun, not an adjective with a noun Unfortunately, dropping hyphens seems to be all the rage nowadays, especially among americans

Anonymous

It's usually joined but separated has a slightly different meaning.