Unnaturally rhymes with:
naturally, naturally, agriculturally, architecturally, culturally, naturally, structurally, agriculturally, architecturally, behaviorally, bilaterally, contradictorily, culturally, federally, generally, liberally, literally, multilaterally, naturally, peripherally, procedurally, structurally, temporally, unilaterally, viscerally
Unnaturally sounds like:
underhill, underlie, underly, unnatural