Regular readers of Grammar Rules know I love homophones. Two frequently used words that share the same pronunciation are bolder and boulder. One is a giant rock, the other is an adjective that means to be braver or more striking.
So let's look at when to use bolder and boulder.
Bolder vs. Boulder
Bolder is a comparative adjective that means more bold. Bold is an adjective with a few meanings: displaying risk-taking ability or bravery; having a vivid or striking visual appearance. So a bolder person may take risks or push the limit with their behavior, while a bolder outfit may combine several bright and/or contrasting colors.
Boulder, on the other hand, is a very big rock. Or it may also refer to a city in Colorado.
Here are a couple examples:
Correct: He is bolder than the shy boy I remember from elementary school.
Incorrect: He is boulder than the shy boy I remember from elementary school.
Correct: She hiked out to the boulder and climbed it.
Incorrect: She hiked out to the bolder and climbed it.
A bolder person may try to move a boulder, but a boulder person is one who likes to climb big rocks (or who lives in Boulder, Colorado). So how I keep these straight: bolder is "bold + er," meaning boulder is the big rock.
No matter what type of writing you do, mastering the fundamentals of grammar and mechanics is an important first step to having a successful writing career.