Unsafe means likely to cause harm. An unsafe building, unsafe practices, declared unsafe.
In law and regulation it is a finding with consequences: an unsafe workplace can be closed, and an unsafe conviction is one quashed on appeal because it cannot be relied on. In ordinary use it is milder than dangerous, which claims active threat. Note safe; and that unsafe covers what might harm rather than what will.
1adjectiveunsafeLikely to cause harm.
“The ice on the lake is too thin and unsafe to walk on.”
synonyms: hazardous, risky
unsafe is a quality of risk.
Proto-Indo-European
*solh₂- — whole, every
Proto-Italic
*salawos
Latin
salvus — whole, safe
Old French
sauf
Middle English
sauf
English
safe
English, today
unsafe
Built from
From un- + safe. safe comes from Middle English sauf, safe, saf, saaf, from Old French sauf, saulf, salf (“safe”), from Latin salvus (“whole, safe”), from Proto-Italic salawos, from Proto-Indo-European solh₂- (“whole, every”). Displaced Old English sicor (“secure, sure”).
Etymology from Wiktionary, CC BY-SA