The Collaborative International Dictionary
Arachnidial
Arachnidial \Ar`ach*nid"i*al\, a. (Zo["o]l.)
Of or pertaining to the Arachnida.
Pertaining to the arachnidium. [1913 Webster] ||
Wiktionary
arachnidial
a. 1 (context zoology English) Of or relating to the Arachnida. 2 (context anatomy English) Relating to the arachnidium.