tuff
n. C1 Advanced US //ˈtəf// UK //tˈʌf// tuff
n. a type of rock made of volcanic ash that has been pressed together over a long time. It is usually soft and has a rough, grainy texture.
n. a rock formed by the consolidation of volcanic ash or other pyroclastic material. It is typically a fine-grained, porous sedimentary rock that is relatively soft and easily eroded.
The cliffs are made of dark grey tuff.
Archaeologists found ancient tools buried in layers of tuff, which helped them date the site accurately.
The geological survey noted that the tuff layer was highly porous, making it an excellent aquifer for the local community but a poor foundation for heavy structures.
From French tuffe, tuf, from Italian tufo, from Latin tōfus. Doublet of tufa.
Eye dialect of tough.