continual, continuous - adjective
Continual: regular or frequent events or occurrences, as in continual trips to the doctor. A good synonym is intermittent.
Continuous: uninterrupted in time or space, as in continuous talking by the people behind you at the movie. A good synonym is uninterrupted.
Note: Most usage guides stress the differences between continual and continuous, but accomplished writers have ignored the distinctions. Consequently, if you need to show that something is continual, use intermittent. If you need to show that something is continuous, use uninterrupted. But a hard distinction remains for spatial relationships, as in a continuous series of doorways, not a continual series of doorways.
It has become Mike Murphy’s new biennial tradition. When the Giants win the World Series, he immediately calls Willie Mays. And then he calls his wife.
Now Enjoying Continual Success, the Giants Will Honor Their Roots David Waldstein New York Times, October 29, 2012
This qualification was clear in a statement that Mr. Romney issued in March, when he called for repeal of the 2010 law and presented his own vision for health care. Mr. Romney said then that he would “prevent discrimination against individuals with pre-existing conditions who maintain continuous coverage.” Thus, aides to Mr. Romney said, he was not breaking new ground with his comments over the weekend.
It Will Be Tricky for Romney to Keep Best of Health Law While Repealing It Robert Pear and Abby Goodnough New York Times, September 10, 2012