adj. & v.
adj. 1 X-shaped. 2 Bot. with pairs of opposite leaves etc. each at right angles to the pair below.
v.tr. & intr. 1 arrange or be arranged in a decussate form. 2 intersect. decussation n.
[ L decussatus past part. of decussare divide in a cross shape f. decussis the numeral ten or the shape X f. decem ten ]