The word Mamihlapinatapai is derived from the Yaghan language of Tierra del Fuego, listed in The Guinness Book of World Records as the "most succinct word", and is considered one of the hardest words to translate. It allegedly refers to "A look that without words is shared by two people who want to initiate something, but that neither will start" or "looking at each other hoping that the other will offer to do something which both parties desire but are unwilling to do."
A romantic interpretation of the meaning also exists: "It is that look across the table when two people are sharing an unspoken but private moment. When each knows the other understands and is in agreement with what is being expressed. An expressive and meaningful silence."... 
The word consists of the reflexive/passive prefix ma- (mam- before a vowel), the root ihlapi (pronounced [i?api]), which means "to be at a loss as what to do next", the stative suffix -n, an achievement suffix -ata, and the dual suffix -apai, which in composition with the reflexive mam- has a reciprocal sense.