BB or 2B

Very black (on lead pencils)

BB

Boys' Brigade

• thiophen
• thiophene
• thiophenes
• thiophens
• thiophil
• thio-salt
• thio-salts
• thiosulphate
• thiosulphates
• thiosulphuric acid
• thiouracil
• thiouracils
• thiourea
• thioureas
• thir
• thiram
• thirams
• third
• Third Age
• Third-Ager
• thirdborough
• thirdboroughs
• third class
• third-class
• third classes