Antonyms of adj riskless

1 sense of riskless

Sense 1
risk-free, riskless, unhazardous -- (thought to be devoid of risk)

INDIRECT (VIA safe) -> dangerous, unsafe -- (involving or causing danger or risk; liable to hurt or harm; "a dangerous criminal"; "a dangerous bridge"; "unemployment reached dangerous proportions")

Similarity of adj riskless

1 sense of riskless

Sense 1
risk-free, riskless, unhazardous -- (thought to be devoid of risk)
       => safe (vs. dangerous) -- (free from danger or the risk of harm; "a safe trip"; "you will be safe here"; "a safe place"; "a safe bet")