Ephemeral and intermittent both describe things that don't last, in different shapes. Ephemeral means brief and unrepeated: one short life, then gone — a soap bubble, a mayfly, a desert stream that runs only while the rain falls. Intermittent means stopping and starting: absent, then back, then absent again — a blinking signal, a seasonal stream. Ephemeral ends; intermittent returns.
The pair are confused almost entirely inside one science: hydrology, which uses both to classify streams that sometimes run dry. An ephemeral stream flows only during and just after rain — typically less than 48 hours — and its bed sits above the water table; it has no memory, only weather. An intermittent stream flows for weeks or months when the seasonal water table rises to feed it, then dries on schedule; it is recurring, half-reliable. Outside the riverbed the words keep the same shapes — ephemeral is the bubble's one short life, intermittent is the stepping stones' endless off-and-on — but it is the streams that send readers to the dictionary.
ephemeral
Ephemeral describes what is here and then gone — beauty, fame, fashions, mayflies. From the Greek ephēmeros, 'lasting a day', it originally described creatures that lived no longer than a single sunrise-to-sunset. Today it carries a wistful, almost poetic tone: to call something ephemeral is not just to say it is brief, but to notice its brevity, the way cherry blossoms are admired precisely because they fall so soon.
intermittent
Intermittent describes what arrives in installments — the Latin intermittere means 'to leave off between', and the gaps are the point: intermittent rain is rain you can walk between; an intermittent signal works right up until it matters. Unlike 'sporadic', which scatters events thinly, intermittent implies an ongoing thing that keeps switching off and on, so you can never quite rely on it and never quite give up on it either.
| ephemeral | intermittent | |
|---|---|---|
| Shape of 'not lasting' | one brief life, then over | off and on, indefinitely |
| Comes back? | never — that was it | yes — that is the point |
| Stream (hydrology) | flows only in and just after rain | flows seasonally, weeks or months |
| Water source (streams) | rainfall only; bed above the water table | rising groundwater, plus rain |
| Classic examples | bubbles, mayflies, fads | faulty signals, monsoon rivers |
| The feeling | poignant — it's gone | exasperating — it's back again |
The bubble and the stones. The bubble is ephemeral: one climb, one pop, one empty space — brevity with no sequel. The stones are intermittent: gone, back, gone, back, on a timetable all their own — absence with guaranteed returns. Ask the only question that separates them: does it come back? No: ephemeral. Yes, again and again: intermittent. A desert flash flood is ephemeral; a monsoon river is intermittent — and a faulty bulb, dark one minute and lit the next, is the second, never the first.
ephemeral
- iCherry blossom is ephemeral by design — a fortnight, then confetti.
- iiDesert wildflowers live ephemeral lives between two rains.
- iiiFame that arrives overnight tends to be equally ephemeral.
intermittent
- iThe cabin has only intermittent phone signal.
- iiIntermittent rain interrupted play all afternoon.
- iiiThe engine developed an intermittent fault no mechanic could catch in the act.
Hydrology's third term completes the classification: a perennial stream flows year-round, fed by a water table its bed never rises above. The trio — perennial, intermittent, ephemeral — orders the world's waterways by reliability, and the dry-country words for the last kind are worth collecting: an arroyo in the American Southwest, a wadi in North Africa and Arabia, a wash in the Mojave — all beds that are footpaths of sand until the storm. Which class a channel falls into can even carry legal weight: under the US Clean Water Act, protection for ephemeral channels has shifted with recent rulings.
TOEFL geography and geology passages use this exact classification — desert hydrology loves arroyos and wadis that flow ephemerally, and a passage may hinge on the groundwater difference: intermittent streams touch the water table, ephemeral ones never do. Ephemeral also stays a favourite vocabulary-in-context target ('short-lived'). Intermittent earns its keep in IELTS description: intermittent rain, intermittent signal — anything that fails and resumes on no fixed schedule.