In French you might say your raison d'etre, your reason for being. It's rare to know this from a young age and sometimes just when you think you know what it is when you get there you realise it isn't it.
Which is a complex one, the drive to do more than just survive and be happy doing it. Within the Japanese word there is a certain joy in finding this. However, as usual, the internet explanations are simplistic. Trying to soundbite a complex viewpoint.
Which is where a spiritual structure can maintain your Ikigai so that it doesn't become lost in the noise of our society.
My structure is yoga, meditation and celebrating the wheel of the year, my Ikigai is cycling, my wife and the drive to create - whether that be gardening or virtual systems it is the creative aspect that appeals.