プログレッシブ和英中辞典(第4版)の解説
ねんいり【念入り】
念入りな（に） 〔慎重な〕careful(ly)；〔手の込んだ〕elaborate(ly)；〔良心的な〕conscientious(ly)
念入りな計画
「a careful [an elaborate] plan
念入りな作品
「an elaborate [a painstaking] piece of work
刑事は何か小さなものを拾い上げると念入りに調べた
The detective picked up something small and examined it carefully [with careful attention/with scrupulous care].
念入りに手を洗った
He washed his hands thoroughly.
出発前に念入りに車を点検した
I checked my car carefully before I left.