Assiduous is an adjective that means showing great care.

The Latin word assiduus (ah see DUECE) means ‘constant’ or ‘persistent.’ This word later evolved into our word of the day which is best used in a context that suggests constant care or attention to a particular goal. For example: I owe a great deal to the assiduous work of the medical staff. Without their around the clock care, I would never have recovered from that agonizing toothache.