Irrespective means it makes no difference — whatever the other thing may be, the result is the same. Everyone pays the same fare, irrespective of age.
The word almost never travels alone: irrespective of is the whole phrase, and dropping the of leaves the sentence unfinished. It is the formal twin of regardless of, and the two are interchangeable in meaning, with irrespective belonging to policies, contracts and official notices. There is a bonus in choosing it: irrespective avoids irregardless, which people reach for when they mix up the pair and which careful writing treats as a mistake.
1adjectiveirrespectiveNot affected by the thing mentioned, used with of.
“The rule applies to all staff irrespective of length of service.”
synonyms: regardless
Latin
respectus
Medieval Latin
respectivus
English
respective
English, today
irrespective
From ir- + respective. respective Borrowed from Medieval Latin respectivus, from Latin respectus. by surface analysis, en + respect + ive.
Etymology from Wiktionary, CC BY-SA