Antonyms of adj time-tested

1 sense of time-tested

Sense 1
tested, time-tested, tried, tried and true -- (tested and proved to be reliable)

INDIRECT (VIA reliable, dependable) -> unreliable, undependable -- (not worthy of reliance or trust; "in the early 1950s computers were large and expensive and unreliable"; "an undependable assistant")
INDIRECT (VIA reliable, dependable) -> unreliable, undependable -- (not worthy of reliance or trust; "in the early 1950s computers were large and expensive and unreliable"; "an undependable assistant")

Similarity of adj time-tested

1 sense of time-tested

Sense 1
tested, time-tested, tried, tried and true -- (tested and proved to be reliable)
       => reliable (vs. unreliable), dependable (vs. undependable) -- (worthy of reliance or trust; "a reliable source of information"; "a dependable worker")