i Register
In some senses, cacuminal is marked as dated. Watch for register when choosing this word.
adj
Pertaining to a point, top, or crown.
Pronounced using a concave or retroflexed tongue; occasionally palatal sounds more generally.
1942, George Leonard Trager, Studies in Linguistics, Volumes 1-7, page 52, /L/ and /N/, slightly more cacuminal than the alveolar series, are very rare, and occur only in word-final position.
The cacuminal s is produced by raising the tongue-tip to a point behind the alveoli, with a concavity in its upper surface;
noun
A sound pronounced using a retroflexed tongue.