cy·ath·e·a·ce·ae \(ˌ)sīˌathēˈasēˌē\noun plural Usage: capitalized Etymology: New Latin, from Cyathea, type genus + -aceae : a family of tropical tree ferns having the sporangia crowded, stalked, and either naked or more often with a cup-shaped indusium — compare silver tree fern • cy·ath·e·a·ceous\(ˈ)sī|athē|āshəs\adjective