from
The Collaborative International Dictionary of English v.0.48
day lily \day" lil`y\, daylily \day"lil`y\(l[i^]l`[y^]). (Bot.)
(a) any plant of a genus of plants ({Hemerocallis})
closely resembling true lilies, but having tuberous
rootstocks instead of bulbs. The common species have
long narrow leaves and either yellow or tawny-orange
flowers, which often bloom for only one day.
(b) A genus of plants ({Funkia}) differing from the last
in having ovate veiny leaves, and large white or blue
flowers.
[1913 Webster +PJC]