The word ikigai (pronounced “eeky-guy”) is a loanword from Japanese, which the Oxford English Dictionary defines as:
ikigai: a motivating force; something or someone that gives a person a sense of purpose or a reason for living.
OED
In kanji, it is represented as 生き甲斐.
Breaking this down into two parts, we have the first part:
iki: 生き: life; alive
For the second part, the psychologist and Professor Akihiro Hasegawa believes the origin of gai within the word derives from kai, which in Japanese means “shell.” (During the Heian period (794-1185), shells were considered valuable). So, for the second part of the word ikigai, we have:
kai: 甲斐: effect; result; fruit; worth; use; benefit; value
For me, this association with shells is important because it suggests (at least historically) there is an economic component to ikigai—something immensely practical in both the medieval and modern world.
REF: Ikigai: A Japanese concept to improve work and life