A look shared by two people, each wishing that the other would initiate something that they both desire but which neither wants to begin.
Yahgan – 1? – Chile and Argentina (Tierra del Fuego)
Actually the gloss popularized is just one possible meaning. The form is analyzed as ma(m)- reciprocal, iləpi 'be ambivalent', -ən-at- 'get into a state', -aːpai dual.
The dictionary compiler (the Rev. Thomas Bridges, who was fluent in Yahgan) often simply put down possible usages as glosses, which later readers misinterpret as fixed definitions. See also: https://en.wikipedia.org/wiki/Mamihlapinatapai
Source: Yamana-English Dictionary (https://archive.org/details/YAMANA-ENGLISHA )
Credit: Jess Tauber