fastidious

Fastidious describes a person or thing that is very particular, meticulous, or demanding about accuracy, cleanliness, or detail. In everyday use, it often suggests a heightened sensitivity to minor imperfections. The word comes from Latin fastidiosus “disdainful, picky,” from fastidium “disgust,” and it entered English via French fastidieux in the early modern period.

A fastidious person tends to pay close attention to standards, preferring order and precision. The term can be neutral or mildly critical, depending on context; it can imply reliability and high standards, or fussiness and inflexibility.

In biology, fastidious describes organisms that require specific nutrients or growth conditions, making them hard to culture. Examples include certain bacteria that need enriched media or particular environmental factors to grow.

Related terms include meticulous, exacting, scrupulous, choosy, and finicky. The connotation of fastidious can vary by context: in a professional setting it may signal thoroughness and high quality, while in casual speech it can imply being overly particular or hard to please.