The Collaborative International Dictionary
Monosepalous
Monosepalous \Mon`o*sep"al*ous\, a. [Mono- + sepal: cf. F. monos['e]pale.] (Bot.) Having only one sepal, or the calyx in one piece or composed of the sepals united into one piece; gamosepalous.
Note: The most recent writers restrict this term to flowers having a solarity sepal, and use gamosepalous for a calyx formed by several sepals combined into one piece. Cf. Monopetalous.
Wiktionary
monosepalous
a. (context botany of a calyx English) having all sepals united