The adverbs continuously and continually (and their corresponding adjectives, continuous and continual) are words that are confused easily and often. Continuously describes an action that happens without ceasing. Continually, on the other hand, describes an action that recurs frequently or regularly.
The confusion about whether to use continually or continuously is understandable, because both words share the same Latin root, continuare, meaning “to join together or connect.” Only the endings of the words are different, and over time, the two words have evolved with subtly distinct meanings.
Define continuously: things that recur nonstop
The most common mistake people make when using these words is to ascribe an action with unintended frequency by using continuously where continually is more appropriate. This results in an exaggeration that will not escape the notice of an editor.
Does she? We all have relatives who can be exasperating at times, but is it possible for your grandmother to correct you continuously? Unless your grandmother is capable of delivering rapid-fire corrections at you with incessant determination, continual is the word you need here.
Let’s try another example.
Talking is an action that is accomplished by human beings, and perhaps parrots. For both, it is almost impossible to do it continuously. I had an aunt who came close; she drew in big gasps between anecdotes so she could continue talking without getting light-headed. But unless a speaker’s “gift of the gab” can match my Aunt Kay’s, chances are they will occasionally pause for breath and await your responses.
If your aim is to underscore the fact that a speaker talked for a period of time in the broader sense before a large-scale interruption occurred, that can merit the word continuously.
Define continually: things that recur frequently
It is quite easy to decide whether to use continuously or continually if you remember to ask yourself, “Did the action ever stop?” Some things do happen continuously and others simply don’t. A clock can tick continuously, and a heart can beat continuously. These actions are automatic. But can lightning strike continuously, for example?
Not only would that be frightening, it would be apocalyptic. You would awaken to a charred landscape that would be quite sobering to behold. Luckily, Mother Nature doesn’t assault us with continuous lightning. On a stormy night, however, it could be continual; that is, it could be happening often and regularly.
Continuous or continual in historical contexts
Continuously may work best when you are writing about a phenomenon that persists over a long period of time in an anthropological, historical, or geological sense. Take this sentence, for example:
The concept here is that buildings that never lapse into disuse are repaired and generally given the attention due to them. While it is not incorrect to say that the Pantheon was used continually (i.e., frequently, in the sense of “it’s amazing how Rome never sleeps”) over the last two thousand or so years, the fact that its use was never interrupted by a period of disuse needs to be highlighted.
Now that you have untangled continuously and continually, you might want to read about other commonly confused English words.