What does “mottainai” mean?
Mottainai (もったいない?, [mottainai]) is a Japanese term conveying a sense of regret concerning waste. The expression “Mottainai!” can be uttered alone as an exclamation when something useful, such as food or time, is wasted, meaning roughly “what a waste!” or “Don’t waste.”
１. When someone leaves the tap water running
This is a very typical situation to use the expression “mottainai.” If you see someone leaving the tap water running, let’s say “mottainai!” Here, this means “It’s a waste of water!”
２. When someone is done eating even though there is still food on the plate
For example in a restaurant, if someone says they’re finished even though there is still food on the plate, you can say “mottainai.” As you see, in this situation it means “It’s a waste of food.” But if it happens in a good and expensive restaurant that you took a train all the way specifically for that,”mottainai” would indicate that it’s a waste of both money and time.
It’s the same at home.
It’s the same at home too. Japanese parents say “mottainai” to their children so children try to finish all their food. Actually in Japan, not finishing everything is impolite to the host who cooked the dish. It can also be considered as being picky. To avoid raising children with bad manners, parents try to encourage their children to finish all their food.
3. When someone doesn’t try something worthwhile
In a conversation with a friend, if you realize that they’ve never tried something you appreciate or you find worthwhile, you can say “mottainai! you should try it!” This “mottainai” means “you should try this” or “you should have tried this.” We use this “mottainai” often in amazement.
When you recommend something
For example, this conversation with a friend can take place.
A: “Hey, this Beatles’ album is awesome. Did you try it?”
B: “Ah no. I don’t listen to popular music.”
A: “You should try this album. It’s mottainai to have such a prejudice.”