Qarin

Rukn (Arabic: ركن; pl. Arkan أركان; meaning "pillar"), in Islamic jurisprudence, refers to an obligatory act, with failure to perform it rendering the act invalid. If a Rukn is neglected, the entire act must be repeated...

A Mufrid (Arabic: مفرد) is a Hajj pilgrim who is performing Hajj al-Ifrad, which involves making one Niyyah for the sole purpose of performing Hajj without Umrah.