Accretion - This word generally means to increase by growth. In the context of the Thousand Islands it is generally used to indicate a shoreline that is growing by addition of sand or other material, rather that being eroded. The sand is usually added by Longshore drift or settling out of suspended material. See Erosion.
Ais - The Ais were people who lived along Florida’s east coast from Cape Canaveral to Jupiter Inlet - after arrival of the Europeans (post-Columbian). The people who lived here before the Europeans arrived were not Ais; we don’t know what to call them. The Ais were named for their Chief in power at the time of discovery by Europeans. Referring to pre-Columbian people as Ais is a common mistake.
Astronomical Tide - A change in water depth caused by the gravitational pull of the sun and moon.