An insect belonging to the suborder Heteroptera. See more at true bug.
An insect, spider, or similar organism. Not in scientific use.
Our Living Language: The wordbug is often used to refer to tiny creatures that crawl along, such as insects and even small animals that are not insects, such as spiders and millipedes. But for scientists the word has a much narrower meaning. In the strictest terms bugs are those insects that have mouthparts adapted for piercing and sucking. The mouthparts of these bugs are contained in a beak-shaped structure. Thus scientists would classify a louse but not a beetle or a cockroach as a bug. In fact, scientists often call lice and their relatives true bugs to distinguish them better from what everyone else calls "bugs."