Uncertainty terms (e.g., possible) are words that are not fixed and hence open to interpretation. This research examined the role of social desirability in how these words are interpreted in self‐report questions. Participants in Experiments 1 (N = 96; MTurk workers) and 2 (N = 96; college students) judged trait (N = 48) and behavior (N = 36) items endorsed by a hypothetical individual to be more likely if they were lower in social desirability. In Experiments 3 (N = 97) and 4 (N = 97) college student participants interpreted four different uncertainty terms (likely, possible, unlikely, and pretty sure) as indicating greater certainty when they referred to socially undesirable (relative to socially desirable) traits (N = 36) and behaviors (N = 24). These results suggest that participants may interpret self‐report items differently, depending on the social desirability of the content.