Noun
1. Plant adapted for life with a limited supply of water; compare hydrophyte and mesophyte. (biology-online.org)
2. An extremophilic organism that can grow and reproduce in conditions with a low availability of water, also known as water activity. Water activity (aw) is a measure of the amount of water within a substrate an organism can use to support sexual growth. Xerophiles are often said to be “xerotolerant”, meaning tolerant of dry conditions. They can survive in environments with water activity below 0.8. Endoliths and halophiles are often xerotolerant. (wikipedia.org)
Word origin: from Greek xēros /ˈzɪroʊs/, meaning “dry”, and philos, meaning “loving”