Be…years somebody’s junior
Definition 1 of 1
Pro Tip 1/3Respectful Distance
Used to show respectful recognition of age difference without emphasizing seniority. 
In meetings, John often acknowledges his colleague, who is ten years his junior, for fresh perspectives.
Pro Tip 2/3Avoid Overuse
Repeatedly pointing out age differences may distract or annoy. Use sparingly to maintain good social relations. 
I mentioned once that Laura is five years my junior, but never dwelled on it again.
Pro Tip 3/3Informal Introductions
Suitable for informal settings when introducing someone notably younger in social or familial contexts. 
At the reunion, I introduced Julie as my cousin, ten years my junior.