n. An old person with impaired intellect; one in his or her dotage.
the GNU version of the Collaborative International Dictionary of English
n. One whose mind is impaired by age; one in second childhood.
The Century Dictionary and Cyclopedia
n. one who is in his dotage or second childhood; one whose intellect is impaired by age.
n. One who is foolishly fond; one who dotes.
n. An aged, decaying tree.
Doting; imbecile.
Decayed, as a tree
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. an oldster in his dotage; someone whose age has impaired his intellect
Word Usage
"Lord Wellington is, for you, only a decayed old gentleman now: I rather think some of you have called him a 'dotard' - you have taunted him with his age, and the loss of his physical vigour."