tan, s. conj. & adv. Lit:1. Time, occasion. 2. Conj. (An) ~, at the time that, when, whenever; since. An ~ do shéan a thriath, when he denied his lord. ~ is tusa do rinne, since it was you who did it. 3. Adv. Once upon a time, once. Do bhí rí ann ~, there was once a king. An ~ sin, at that time, then. Iar dtain = iardain.