SPEND enough time at the playgrounds of Prospect Park, Brooklyn, on a typical summer morning and you’ll eventually hear every conceivable nickname for a toddler: Bobo, Little Man, Monster Face.

But for all the individuality on display (ask a parent about a nickname and you’re guaranteed an adorable back story), the one term heard far more than any other is generic, reflexive and not particularly creative. It might also have the most to say about modern approaches to parenting.

“O.K., buddy, O.K.!” said a father recently, caving to his son’s demands to be chased. “Nice work, buddy,” said another father crouched low in a sandbox. “Come on buddy, let’s dry you off,” said a mother recently to her half-naked, Croc-wearing puddle jumper.

Like “sport” or “champ” of an earlier era, “buddy” has quietly evolved over the last 20 years into the go-to nickname for American parents, particularly fathers, looking to chum it up with their sons and daughters. How it got there is hard to say; good luck finding an adult who remembers his dad calling him buddy. But like “time out” and “use your words,” “buddy” has for better or worse taken a starring role in the lexicon of modern American parenting.