ˌ ̷ ̷ ̷ ̷+ˈthēkə noun
Etymology: New Latin, from hydr- + Latin theca sheath, case — more at tick
: a cup-shaped extension of the perisarc in hydroids of the group Leptomedusae that surrounds and protects the hydranths when they are contracted
• hy·dro·the·cal | ̷ ̷ ̷ ̷|thēkəl adjective