Not flagging; untiring. See Synonyms at tireless.(adjective)
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 "unflagging" in a sentence
"Defence lawyer Sean May, who asked for three to six months in jail, said his remorseful client has no criminal record, welcomes treatment and has the "unflagging" support of his wife"
"She never bristled at being told what to do, issuing her oídos with an unflagging enthusiasm that would have made you think she was volunteering for a second ice cream cone rather than agreeing to lug a crate of vegetables back from the walk-in."
"Many of the qualities that come so effortlessly to dogs -- loyalty, devotion, selflessness, unflagging optimism, unqualified love -- can be elusive to humans."