mid-15c., "being of the third power;" 1550s, "having the form of a cube," from Old French cubique (14c.), from Latin cubicus, from Greek kybikos, from kybos "cube" (see cube (n.)). Meaning "solid, three-dimensional" is from 1650s.
Cubical is attested from 1590s with the meaning "of or pertaining to a cube," and according to OED it is "Now more usual than cubic in this sense." Related: Cubically.
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}