recklessness (n.)

Middle English recheles, from Old English receleas "careless, thoughtless, heedless," earlier reccileas, literally "not recking (of consequences)" from *rece, recce "care, heed," from reccan "to care" (see reck (v.)) + -less. The same affixed form is in German ruchlos, Dutch roekeloos "wicked."

The root verb reck (Old English reccan) is passing into obscurity; the range of Middle English spellings might reflect uncertainty even then about it, e.g. rechiles, retcheles, recelease, richeles, regeles, reccles, rakeles. 

word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).