I found myself writing 'to his chagrin' yesterday and wondered about the rather strange word 'chagrin'. I cannot think of any other common English words that end in 'grin', apart from 'grin' itself.
Chagrin comes from French and was originally a type of rough, abrasive leather. This sense is now spelled shagreen in English. In French chagrin came to have a figurative usage, namely 'displeasure' or 'vexation' and this also passed into English, which is the common meaning of 'chagrin' these days.
The OED notes that circa 1700 the word was often referred to as 'an affected and frenchified term'.
The 19th-century French novelist Balzac wrote a book entitled La Peau de Chagrin (lit. skin of rough leather). The story concerns a young man who finds a piece of shagreen, which grants his every wish. However, each time a wish is granted the shagreen shrinks in size and the young man loses some of his physical energy. When the shagreen shrinks to nothing, the young man dies.
Peau de chagrin is now an entry in its own right in the Oxford English Dictionary, with the definition/ explanation "Used allusively to indicate the progressive diminution of something, esp. the human lifespan".