definitely 是副词，表示「毫无疑问地，确实」：I definitely agree（我肯定同意）；definitely not（绝对不：this is definitely not acceptable = 这绝对不可接受）；definitely worth doing（绝对值得做）。注意拼写：definitely（× definitly，× definately——常见拼写错误）。辨析：definitely（肯定地，强调「毫无疑问」：definitely the best option = 无疑是最佳选项）vs. certainly（当然，也表确定，但更常用于礼貌应答：certainly，can I help you? = 当然可以）vs. clearly（清楚地，显然：clearly this is wrong = 显然这是错的；强调「从证据可见」）vs. undoubtedly（毫无疑问地，书面正式：undoubtedly the most significant = 毫无疑问是最重要的）。
释义
1
adv.肯定地，确实，无疑地
The new public transport system has definitely reduced traffic congestion in the city centre, with commute times falling by an average of twenty minutes.
新的公共交通系统确实减少了市中心的交通拥堵，通勤时间平均缩短了20分钟。
2
adv.绝对地（用于强调否定或肯定）
Definitely not — the proposal contradicts the organisation's core values and should be rejected without further consideration.
绝对不行——该提案与组织的核心价值观相悖，应予以拒绝，无需进一步考虑。
语感
definitely the best（无疑是最好的）；definitely not（绝对不）；definitely worth（绝对值得）；most definitely（最肯定地，强调）；I'm definitely going（我肯定去）
肯定地，确实（definitely the right choice = 肯定是正确的选择）绝对（definitely not = 绝对不）
高频搭配：definitely the best / most important（无疑是最好的/最重要的）；definitely not（绝对不：definitely not acceptable = 绝对不可接受）；definitely worth doing / seeing（绝对值得做/看）；most definitely（最肯定地，加强语气：most definitely agree = 非常肯定地同意）；I'm definitely going / doing（我肯定去/做）；注意：definitely 修饰形容词、动词、全句；辨析：definitely（无疑，强调主观确信）vs. certainly（当然，也可表客气应答：certainly! = 当然！；比 definitely 更礼貌中性）vs. clearly（清楚地，强调从外部证据可见：clearly the results show = 结果清楚显示）vs. undoubtedly（毫无疑问，书面：undoubtedly the most = 毫无疑问是最…；比 definitely 更书面正式）。
陷阱
⚠️definitely（× definitly / × definately）——高频拼写错误
The report concludes that investment in early childhood education is definitely one of the most cost-effective strategies for improving long-term social outcomes.
⚠️definitely not（绝对不）vs. not definitely（不一定）——语序改变语义
✗
The committee has not definitely ruled out the possibility of a second referendum, though no decision has been announced.
委员会尚未明确排除第二次公投的可能性，尽管尚未宣布任何决定。（not definitely = 尚未明确地；vs. definitely not = 绝对不）
not definitely（不一定，= 尚未明确地）vs. definitely not（绝对不 = 强烈否定）；此句 has not definitely ruled out = 尚未明确排除（仍有可能），意思是「委员会没有明确地排除第二次公投的可能性」；若写 has definitely not ruled out = 绝对没有排除（更强调仍有可能）；两者均可接受，语序不同改变强调重点；注意不混淆
✓
The committee has definitely not ruled out the possibility of a second referendum — it remains an option under active consideration.
委员会绝对没有排除第二次公投的可能性——这仍是一个正在积极考虑的选项。（definitely not = 绝对没有排除；强调可能性仍存在）
近义辨析
definitelyvsundoubtedly
definitelydefinitely（肯定地：this is definitely correct = 这肯定是对的；口语书面均用，强调说话者的主观确信）undoubtedlyundoubtedly（毫无疑问地，书面正式：this is undoubtedly the most significant finding = 这毫无疑问是最重要的发现；比 definitely 更书面，更客观，常用于议论文和学术写作）
The new policy will definitely face opposition from some stakeholders, but the overall benefits outweigh the short-term disruption.
新政策肯定会遭到一些利益相关者的反对，但总体利益超过短期的干扰。
This technological breakthrough is undoubtedly the most significant development in renewable energy research in the past decade.
这一技术突破毫无疑问是过去十年可再生能源研究中最重要的进展。
写作加分
✨ 加分词
替换：for suretotally100%
议论文写作政策分析话题社会问题议论文
普通
For sure, social media has a big impact on young people's mental health.
毫无疑问，社交媒体对年轻人的心理健康有很大影响。
加分 ✨
Research definitely supports the view that excessive social media use is associated with elevated rates of anxiety and depression among adolescents — a finding replicated across multiple countries and age groups.