Let's face it, we've already stolen the words bong (the pipe) and pad thai from Thai, so one more word won't make much difference.
Greng-jai is a complicated thing. It can be the reluctance you feel when about to ask a favour from someone, or the reluctance you feel in interfering in any way with someone else's behaviour, even when it's plainly wrong or even illegal.
Greng-jai is more or less the opposite of confrontation.
As this leads to all sorts of not-saying-what-you-mean, I suppose this is the opposite of effective language.
But it'd be a jolly useful word, all the same.
Word To Use Today: greng-jai. This word is Thai. Jai means heart mind or spirit and greng means fear or to be afraid.