Ma'anar ƙamus na kalmar "layin tsakiya" na nufin layin da ya ratsa cikin ainihin tsakiyar abu ko sarari, ya raba shi gida biyu daidai gwargwado. Hakanan yana iya komawa zuwa layin da ke alamar tsakiyar hanya ko layi, ana amfani da shi azaman jagora don zirga-zirga. Kalmar "layin tsakiya" ana amfani da ita a aikin injiniya, gine-gine, da gine-gine don nufin madaidaicin layi wanda ake amfani da shi azaman ma'auni don ma'auni da daidaitawa.