Adjective:
lacking or indicating lack of confidence or assurance;uncertain of his convictions
unsure of himself and his future
moving with uncertain or unsure steps
an uncertain smile
touched the ornaments with uncertain fingers
not established beyond doubt; still undecided or unknown;an uncertain future
a manuscript of uncertain origin
plans are still uncertain
changes of great if uncertain consequences
without further evidence his story must remain uncertain
not established or confirmed;his doom is as yet unsealed
not certain to occur; not inevitable;everything is uncertain about the army
the issue is uncertain
subject to change;a changeable climate
the weather is uncertain
unsettled weather with rain and hail and sunshine coming one right after the other
not consistent or dependable;an uncertain recollection of events
a gun with a rather uncertain trigger
ambiguous especially in the negative;she spoke in no uncertain terms
questionable，doubtful，ambiguous，uncertain这些形容词均含“怀疑的，不确定的”之意。
questionable通常指怀疑某行为是否恰当，或指有根有据的怀疑。
doubtful指对某个问题持积极怀疑的，有疑问的态度，强调缺乏确信。
ambiguous指因缺乏明确感或因为有各种不同的解释而值得怀疑。
uncertain多指因缺乏证据或了解而捉摸不定，也指因不能预料而不能作出选择。
in no uncertain terms用十分明确的言词…uncertain of对 … 不确知…uncertain about对 … 不确知的…be uncertain about对 … 不确定…be uncertain of不能确定uncertain knowledge不确定知识uncertain relation不定关系market uncertain市场涨落不定…uncertain system不确定系统uncertain inference不确定性推理…uncertain prognosis预后难定uncertain rate不确定汇率uncertain reasoning不确定推理uncertain region不可辨区, 不确定区…
近义词 hazy朦胧的risky危险的adrift漂流地erratic古怪的flighty轻浮的dubious怀疑的vague不明确的unsure不肯定的doubtful可疑的confused困惑的hesitant迟疑的inexact不精确的unclear不清楚的changeable易变的insecure不安全的bewildered困惑的fickle变幻无常的contingent代表团indefinite模糊的unsealed未密封的speculative推测的conjectural推测的tentative不确定的undefined未定义的unsettled未处理的incertain不确定的precarious不稳定的questionable可疑的in doubt不能肯定的unreliable不可靠的ambiguous模棱两可的equivocal模棱两可的adventurous爱冒险的irresolute优柔寡断的capricious变化无常的indecisive犹豫不决的indeterminate不确定的unpredictable不可预知的undecided胜负未决定的…dispossessed被剥夺财产的…debatable有疑问的，有争议的…反义词 certain确定的
形容词99%,名词1%
用作形容词Life on earth is short and uncertain.地面上的生命是短暂而不确定的。
This is a very uncertain time for the global economy.当前全球经济正面临一个极不稳定的时期。