lichen

About 1.05 uses per million words.

Meaning

1. noun Any of many symbiotic organisms, being associations of algae and fungi, often found as white or yellow-to-blue–green patches on rocks, old walls, etc.
2. noun Something which gradually spreads across something else, causing damage.
3. verb To cover with lichen.

Similar words

crustose foliose fruticose moss species paw vascular warming boreal nitidus

Often followed by

planus and sclerosus simplex on is species ruber flora

Word family

lichened lichenous lichens