Singers with a range from F3 to F5

ALTOS

This vocal part often harmonizes above sopranos in choral music but below the highest female range.

This clue refers to a vocal range typically found in female singers who fall between sopranos and tenors. Altos usually sing in the lower to middle register, spanning from around F3 to F5, which matches the given note range. The term is commonly used in choral music to describe this specific voice type, making "ALTOS" the straightforward answer. No wordplay is involved—it’s a direct definition.