I'm continually confused by this word

continual / kên-tin-yu-êl / adjective

Repeated over a long period of time, continuing at intervals.

Robert Beard, who holds a PhD in linguistics and calls himself Dr. Goodword, explains continual and its evil relationship with continuous.

Continual is often confused with continuous. However, the meanings of these two words differ significantly and they cannot be used correctly as synonyms.Continuous refers to an action that continues in an unbroken fashion, as a continuous hum or buzzing sound. Continual refers to a repeated action that is periodically interrupted, as continual complaints about the dog from the neighbors. 

If your spouse continuously nagged you, his or her mouth would never close, so nagging tends to be continual, off and on: "Bea Heine's continual nagging makes her husband's life a continuous nightmare." Here is a mnemonic sentence that will help you keep these two adjectives straight: "I must remind myself continually that life goes on continuously.

History: This sometimes confusing word originates from the same Latin adjective, continuus, as does continuous but with the substitution of the suffix -al for Latin -us. Continual comes from the verb continere "to hold together" made up of con "together, with" + tenere "to hold, keep". The root *tend- in the Proto-Indo-European, the origin of most of the languages of Europe and India, apparently meant "stretch", judging from Greek teinein "stretch," Sanskrit tantram "loom," and Latin tendere "stretch". The Latin root was borrowed into English in words suggesting stretching, such as tendon, tend, tense, tenuous, and tent. The English derivative is thin, which is how things get when stretched.