مَتَى رَاجَعْتُمُ السِّجِلَّاتِ؟ — أَمْسِ.
When did you review the records? — Yesterday.
The question already supplies the event “reviewed” and its object “the records,” allowing the answer to consist of the time alone. The intended fuller response, “We reviewed them yesterday,” is recoverable from the stated question. The omitted material is grounded in a clear linguistic clue, not invented merely because the answer is short.
Outside this exchange, the isolated word “yesterday” may leave the listener unsure which event it refers to. Thus the legitimacy and effectiveness of ellipsis depend on shared context. Brevity is eloquent when the required meaning is preserved, not simply whenever fewer words are spoken.