Irrespective means without being influenced by something or without taking something into account. When you make a decision irrespective of cost, you don't let price affect your choice. When a teacher grades irrespective of how much she personally likes each student, she evaluates everyone's work by the same standards, regardless of her feelings.

The word almost always appears in the phrase “irrespective of,” followed by whatever factor is being set aside or ignored. A coach might say she'll choose team captains irrespective of popularity, meaning she'll focus only on leadership ability and dedication, not who has the most friends. A scientist conducting an experiment must record results irrespective of whether they support her hypothesis.

Irrespective is similar to regardless, and the two words can often be used interchangeably. Both suggest a deliberate choice not to let certain factors influence you. When someone acts irrespective of the consequences, they move forward with their decision no matter what might happen. When rules apply irrespective of age or experience, they apply to everyone equally, whether you're new or have been around for years.