Definition: (noun) blessing; benefit
Also Known As: boost; benefit
Common Misspellings: boom
Examples: The sudden snow shower was a real boon to the ski industry in the state.
In a Quote:
To breathe deeply, to exercise regularly, to sleep soundly, and to eat nutritious food, avoiding sweets and eschewing pickles and condiments, are among the business woman's cardinal necessities. Her dress must be neat and simple; the shirt waist has been a boon to her, because it may be dainty, unobtrusive and inexpensive, and in it she looks like the lady she is.
From Winsome Womanhood, by Margaret E. Sangster, published in 1901.

