'dialysepalous' originates from New Latin, formed by combining the Greek-derived element 'dialy-' (from Greek 'dialusis/dialysis' meaning 'separation') and Modern Latin 'sepalum' meaning 'sepal'.

'dialysepalous' was coined in modern botanical Latin (19th–20th century) by combining Greek and Latin elements used in botanical morphology and was adopted into English botanical terminology without major change.

Initially the components referred broadly to 'separation' and 'sepal'; in botanical use the compound came to specifically denote 'sepals that are separate (not fused)'.