This one is easy for me. My favourite word is 'Ikigai'- which is Japanese and translates roughly as 'reason for being' or 'thing which gets you out of bed in the morning'. I love words that cannot be translated directly from one language to another. I have my own slow-fashion label and actually use words like this to name all my products because I love the idea of a feeling or emotion being represented by one untranslatable word.