Mamihlapinatapai

I came across the above word for the first time recently.

This is from Wikipedia

Mamihlapinatapai (sometimes misspelled mamihlapinatapei) is a word from the Yaghan language of Tierra del Fuego, listed in TheGuinness Book of World Records as the "most succinct word", and is considered one of the hardest words to translate. It describes a look shared by two people with each wishing that the other will initiate something that both desire but which neither one wants to start. This could perhaps be translated more succinctly as "eye-contact implying 'after you...'". A more literal approximation is "ending up mutually at a loss as to what to do about each other".
The word consists of prefix ma(m)- reflexive/passive (second m before roots beginning with a vowel), root ihlapi (hl as in welsh ll, though in Yahgan it has also been described as similar to sl) which means to be at a loss as to what to do next, followed by stative suffix -n- and achievement suffix -at(a), and finally dual -apai, which in composition with ma(m)- has a reciprocal sense.
It is also the title of a song by American singer Ronny Cox.