This is the 13081st most frequent German word.
achtlos
"Without care or attention; heedless; careless."
In this sentence, 'achtlos' is used to describe the manner in which the book was placed, indicating that it was done without attention or care.
Er legte das Buch achtlos auf den Tisch.
He placed the book carelessly on the table.
Here, 'achtlos' is used as the noun 'Achtlosigkeit' to signify a general state or quality of being careless.
Achtlosigkeit kann zu unerwarteten Problemen führen.
Carelessness can lead to unexpected problems.
In this example, 'achtlos' suggests that the action of walking past the sign was done with a lack of awareness or attention.