Conditional clauses in Latin are clauses which start with the conjunction sī 'if' or the equivalent. Other possible conjunctions are sīn 'but if', siquidem 'if indeed' and sīve or seu 'whether', and if negative sī ... nōn, nisi 'unless', nī 'if ... not'. Sometimes the conjunction is omitted. The 'if'-clause in a conditional sentence is known as the protasis, and the consequence is called the apodosis. Conditional clauses sometimes overlap in meaning with other types of clause, such as concessive ('although'), causal ('in view of the fact that'), or temporal ('whenever').