Definition: Anosmia means being unable to detect certain smells because they are present in low concentrations. It's described as "smellless" or "scentless." The term has roots from Greek, where it translates roughly to "darkness" or "mystery," referring to lack of sight or understanding. This symptom can affect a person's ability to detect even the most subtle odors and is often related to nasal issues like allergic rhinitis or chronic sinusitis.