assiduous
adjective /əˈsɪdʒuəs/
/əˈsɪdʒuəs/
(formal)- working very hard and taking great care that everything is done as well as it can be synonym diligent
- one of the most assiduous members of the team
- their assiduous efforts and attention to detail
- She was assiduous in her duties.
Word Originmid 16th cent.: from Latin assiduus, from assidere ‘be engaged in doing’ from ad- ‘to, at’ + sedere ‘sit’, + -ous.