early 14c., from O.Fr. deien, from L.L. decanus "head of a group of 10 monks in a monastery," from earlier secular meaning "commander of 10 soldiers" (which was extended to civil administrators in the late empire), from Gk. dekanos, from deka "ten." Replaced O.E. teoðingealdor. College sense is from 1570s (in L. from 1271).