Is there a difference between tepid water and lukewarm water? Are the terms interchangeable?
The terms are interchangeable.
There is no difference, thus the terms are interchangeable.
Tepid water consists of two parts cold water and one part boiling water, which renders a temperature of about 40 degrees Celsius, which is round about 105 degrees Fahrenheit.
Luke warm water is also considered in the same temperature range, which concludes that both are the same.
A quick test would be that the water to the touch should just be a bit warmer that normal body temperature and should not burn you
In my experience "tepid" means "room temperature" whereas "lukewarm" means "just barely warm". So I'd rate tepid as just slightly cooler. But that's splitting hairs. In practical terms -- ie in recipes -- they're interchangeable.
While today using “luke” to mean “warm” has gone out of fashion, possibly due to the popularity of the name “Luke”, at one time that’s what the word meant. This came from the fact that “luke” derived from “lew” or “lewk” or “leuk”, in Middle English, which meant “tepid” (slightly warm).
According to dictionary.com, tepid means:
1. moderately warm; lukewarm: tepid water.
2. characterized by a lack of force or enthusiasm: tepid prose; the critics' tepid reception for the new play.
Tepid water by definition (medically speaking) is between 24 degrees(c) and 33 degrees(c). Not 40c as stated in an earlier comment. That comment is way off and could be dangerous if used as a guide to bath babies!!
Teped water in COOKING is in fact 30-40 degrees Celsius, 86 to 90 degrees Farenhight.
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