The word ‘Mamihlapinatapai’ is thought to be one of the most difficult words to translate. Derived from Yaghan, an indigenous language of Tierra del Fuego, it’s listed in The Guinness Book of World Records as the ‘most succinct word,’ and refers to “a look shared by two people, each wishing that the other would initiate something that they both desire but which neither wants to begin.” Source Source 2 Source 3