Irrespective of / Regardless of / regardless / Irrespectively / Irregardless
Regional usageUse irrespective of or regardless of. Avoid irrespectively and irregardless in formal Singapore workplace writing.
Irrespective of
Use when
You mean without considering or being affected by a stated factor.
Example
“The policy applies irrespective of grade.”
Regardless of / regardless
Use when
You mean without considering or being affected by something; regardless may also stand alone.
Example
“The policy applies regardless of grade.”
Irrespectively
Use when
Avoid this obsolete or informal form in formal Singapore workplace writing; use irrespective of or regardless of.
Example
“Replace 'irrespectively of grade' with 'irrespective of grade'.”
Irregardless
Use when
Avoid this nonstandard form in formal Singapore workplace writing; use regardless or irrespective.
Example
“Replace 'irregardless of grade' with 'regardless of grade'.”
Quick check
irregardless, irregardless of, irrespectively, irrespectively of
Usage note
Irregardless and irrespectively are recorded in some dictionaries, but with nonstandard, obsolete or informal labels. Treat them as forms to avoid rather than claiming that they have never existed.