Mar·tel·lo tower 
(mär-tĕlō)
(mär-tĕlō)n.
A short, circular tower, usually made of stone and located near a shoreline as a defensive fortification.
[After Cape Mortella, Corsica, where such a tower was taken from French control by British forces in 1794 (influenced by Italian martello, hammer, in torre di martello, hammer tower, a kind of watchtower of the coasts and islands of the Tyrrhenian Sea from which an alarm signal was given by striking a bell with a hammer rather than by lighting a fire).]
- tête-bêche
- tête-à-tête
- Tínos
- Tórshavn
- tôle
- tögrög
- Tübingen
- U
- directed angle
- directed distance
- direct examination
- direct free kick
- direction
- directional
- directional antenna
- directionality
- directional signal
- direction finder
- directionless
- directive
- directly
- direct mail
- direct-mail
- direct mailer
- direct object