The complete performance of an investment over a period, combining both the change in its price and any dividends or distributions paid along the way — usually expressed as a percentage.
Looking at price alone can be misleading. A stock that barely moves in price but pays a steady 4% dividend every year has actually performed quite well — just not in a way a simple price chart shows. Total return adds the two pieces together (price change + income received) to give the real, complete answer to "how did this investment actually do for me?"
A fund whose share price grew 5% in a year and also paid a 3% dividend has a total return of roughly 8% — even though a headline chart of just the price might only show the 5%. This is why comparing a low-yield growth fund to a high-yield income fund purely on dividend size misses half the story.