anti-royalist
Anti-monarchist protesters defied a curfew to march on the capital.
The announcement was greeted with delight by MPs with anti-monarchist views.
He is not particularly anti-monarchist.

SMART Vocabulary: related words and phrases

Royalty, aristocracy & titles
accede to something
accession
anointed
anti-monarchical
anti-royalist
dukedom
earl
earldom
emir
emperor
mister
monarch
monarchist
morganatic
Mr
royally
Rt. Hon.
Shah
sheikh
sire
anti-monarchist
noun[ C ]
(alsoantimonarchist)uk /ˌæn.tiˈmɒn.ə.kɪst/ us /ˌæn.t̬iˈmɑː.nɚ.kɪst//ˌæn.taɪˈmɑː.nɚ.kɪst/
a person who is opposed to a king or queen, or to the idea of their country being ruled by a king or queen:
An anti-monarchist, he was a prominent member of the Republican Society.
Anti-monarchists called for a scaling-down of the royal family.
Synonym