Noun
large primitive predatory aquatic insect having two pairs of membranous wings
Source: WordNetThe longest living odonate is the Neotropical helicopter damselfly Mecistogaster linearis (Zygoptera: Pseudostigmatidae) with a body length of 135 mm. Source: Internet
Sometimes the giant Hawaiian darner Anax strenuus (Anisoptera: Aeshnidae) is claimed to be the largest living odonate with an alleged wing span of 190 mm, but this seems to be rather a myth as only 152 mm are scientifically documented. Source: Internet