tufa /tooˈfə, tūˈfə/

1. Calc-sinter (often calcareous tufa)
2. Tuff or other porous rock (obsolete)

• knottiest
• knottily
• knottiness
• knottinesses
• knotting
• knottings
• knotty
• knotweed
• knotweeds
• knotwork
• knotworks
• knout
• knouted
• knouting
• knouts
• know
• knowable
• knowableness
• knowablenesses
• know a hawk from a handsaw
• know-all
• know-alls
• know all the answers
• know a man by his company
• know a move or two