assiduous (adj.)
- advertent
- agog
- alert
- ardent
- attentive
- aware
- careful
- concentrated
- conscious
- constant
- continuing
- diligent
- dogged
- earnest
- elaborate
- enduring
- energetic
- faithful
- fervent
- finical
- finicky
- hard
- hardworking
- heedful
- immutable
- inalterable
- indefatigable
- indomitable
- industrious
- insistent
- intense
- intent
- invincible
- laborious
- lasting
- loyal
- meticulous
- mindful
- nice
- niggling
- observant
- observing
- obstinate
- open-eyed
- openmouthed
- operose
- painstaking
- patient
- permanent
- persevering
- persistent
- persisting
- pertinacious
- plodding
- preoccupied
- rapt
- regardful
- relentless
- resolute
- sedulous
- single-minded
- sleepless
- stable
- steadfast
- steady
- strenuous
- stubborn
- tenacious
- thorough
- thoroughgoing
- tireless
- unconquerable
- undaunted
- undiscouraged
- unfailing
- unfaltering
- unflagging
- unflinching
- uninterrupted
- unrelenting
- unremitting
- unsleeping
- unsparing
- unswerving
- untiring
- unwavering
- unwearied
- unwearying
- vehement
- watchful
- zealous
