any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter | (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work |
| the 19th letter of the Roman alphabet |
| a unit of conductance equal to the reciprocal of an ohm |
| the cardinal compass point that is at 180 degrees |
| an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions) |