• 倹約けんやく — frugality; saving money; being economical
• 倹約家けんやくか — a thrifty person; someone who lives frugally
• 勤倹きんけん — diligence and frugality
• 質素倹約しっそけんやく — a simple and frugal lifestyle
• 倹けん素そ — plain and modest; not luxurious

倹 is a phono-semantic character. The left side 亻 is the “person” radical, and the right side comes from a phonetic element that also appears in words about gathering or managing. Together they suggest a person who manages resources carefully — cutting waste, saving what can be saved, and living within their means.