If you see a danger sign, it means that there is something harmful or risky in the vicinity. However, there are various synonyms for this phrase that can also convey the same message. These synonyms include warning sign, caution sign, hazard sign, alert sign, and red flag. Whether it's a construction site, a hazardous materials storage area, or a busy road, these signs are crucial for keeping people safe and avoiding accidents. So the next time you see one of these signs, remember to take heed and follow any necessary safety precautions.