A person of relatively advanced age, especially a person at or over the age of retirement.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "senior citizen" in a sentence
"He’s in every one of them and my hope is that we’ll try a few out when he returns stateside and before, you know, I become the cane-wielding senior citizen you obviously think I am."