Definify.com
Webster 1913 Edition
Pyramidal
Py-ramˊi-dal
,Adj.
[Cf. F.
pyramidal
.] 1.
Of or pertaining to a pyramid; in the form of a a pyramid; pyramidical;
as,
. pyramidal
cleavageThe mystic obelisks stand up
Triangular,
Triangular,
pyramidal
. Mrs. Browning.
2.
(Crystallog.)
Same as
Tetragonal
. Pyramidal numbers
(Math.)
, certain series of figurate numbers expressing the number of balls or points that may be arranged in the form of pyramids. Thus 1, 4, 10, 20, 35, etc., are triangular pyramidal numbers; and 1, 5, 14, 30, 55, etc., are square pyramidal numbers.
Webster 1828 Edition
Pyramidal
PYRAM'IDAL
,Adj.