As a noun emphasiser
is .
As a verb emphasises is
(emphasise).
emphasises
English
Verb
(head)
(emphasise)
emphasise
English
Verb
(emphasis)
(British)
Usage notes
The "s" spelling has co-existed with the "z" spelling for at least 150 years (Thackeray wrote
emphasised ), and is becoming more common in the UK, with the "z" spelling gradually falling out of usage.
British English forms