昨晚 (zuó wǎn) is a concise compound meaning last night or yesterday evening. 昨 means yesterday and 晚 means evening or late. It is a more compressed form of 昨天晚上 (zuó tiān wǎn shàng), which carries the same meaning but spells out both day and time of day. 昨晚 is common in both speech and writing when referring to the previous evening. Its counterpart for today's evening is 今晚 (jīn wǎn) and for tomorrow evening 明晚 (míng wǎn).