English Advanced Vocabulary for C1/C2 Learners
CEFR C1-C2 • Vocabulary • 50 high-leverage advanced words that signal upper-intermediate to advanced fluency
Why a small vocabulary upgrade signals C1/C2
The gap between B2 (upper-intermediate) and C1/C2 (advanced) is not about knowing more words — it is about knowing the RIGHT words. A C1 speaker says "this approach is unviable" instead of "this approach will not work." A C2 speaker uses "ostensibly," "tantamount to," and "in lieu of" naturally. This page covers the 50 advanced words that mark fluency, with click-to-listen pronunciation and real business examples.
Hedging and qualification (10 words)
| Word | Meaning | Example |
|---|---|---|
| ostensibly | apparently / on the surface | "Ostensibly, the project is on track, but I have concerns." |
| arguably | it could be argued | "This is arguably the most important release of the year." |
| presumably | based on reasonable assumption | "Presumably, the customer will renew once they see the new feature." |
| conceivably | it is possible to imagine | "Conceivably, we could ship by Q2 — but it is tight." |
| presumed | assumed without proof | "He is presumed innocent until proven otherwise." |
| seemingly | appearing to be | "A seemingly small bug caused a $200k loss." |
| nominally | in name only | "She is nominally the CTO, but the founder still makes all calls." |
| tentatively | provisionally | "We have tentatively scheduled the launch for September." |
| unequivocally | without doubt | "This is unequivocally the best path forward." |
| conditionally | depending on conditions | "Approval was given conditionally on a security review." |
"Ostensibly, the project is on track. Arguably, the bigger risk is the dependency on legal review."
Quantification and emphasis (10 words)
| Word | Meaning | Example |
|---|---|---|
| negligible | very small / unimportant | "The cost increase is negligible — under $500." |
| substantial | considerable | "There is substantial evidence supporting this hypothesis." |
| considerable | significant amount | "This will require considerable engineering effort." |
| marginal | slight / on the edge | "The improvement is marginal — not worth the deploy risk." |
| incremental | in small steps | "We are taking an incremental approach to the refactor." |
| disproportionate | out of fair proportion | "The cost is disproportionate to the benefit." |
| predominantly | mostly / mainly | "Our customers are predominantly enterprise-tier." |
| overwhelmingly | by a large margin | "The board overwhelmingly supported the proposal." |
| profoundly | deeply | "This will profoundly change how we operate." |
| imperceptibly | too small to notice | "Latency increased imperceptibly — only the dashboards caught it." |
"The cost increase is negligible, but the impact on customers is substantial."
Cause and effect (10 words)
| Word | Meaning | Example |
|---|---|---|
| consequently | as a result | "The migration was delayed; consequently, the launch slipped." |
| thereby | by that means | "We automated the deployment, thereby reducing human error." |
| hence | therefore | "The data is incomplete; hence, our findings are preliminary." |
| inasmuch as | to the extent that | "Inasmuch as the data is reliable, we can proceed." |
| insofar as | to the degree that | "Insofar as the customer is willing to pay, this works." |
| precipitate | cause to happen suddenly | "The leak precipitated a full security review." |
| engender | cause / give rise to | "The new policy engendered some resistance." |
| contribute to | help cause | "Three factors contributed to the outage." |
| attributable to | caused by | "The decline is attributable to seasonal factors." |
| tantamount to | equivalent to (often negative) | "Skipping the security review is tantamount to negligence." |
"The migration was delayed; consequently, the launch slipped. The slippage is attributable to the unexpected security review."
Critical evaluation (10 words)
| Word | Meaning | Example |
|---|---|---|
| scrutinize | examine carefully | "The proposal will be scrutinized by the board." |
| discernible | noticeable / detectable | "There is no discernible improvement in the latest version." |
| tenable | defensible / can be maintained | "This position is no longer tenable given the new data." |
| untenable | cannot be defended | "The status quo is untenable — we must change." |
| plausible | believable | "That is a plausible explanation, but we need data." |
| implausible | unlikely / hard to believe | "The 6-week timeline is implausible without doubling the team." |
| questionable | doubtful | "The methodology in section 3 is questionable." |
| compelling | strongly persuasive | "The data presents a compelling case for the redesign." |
| nuanced | subtle / fine-grained | "This requires a more nuanced view." |
| cogent | clear and convincing | "She made a cogent argument for restructuring." |
"The data presents a compelling case, but the methodology is questionable. We need a more nuanced approach."
Formal substitution (10 words)
| Casual | Advanced | Example |
|---|---|---|
| instead of | in lieu of | "Stock options were given in lieu of a higher base salary." |
| about | regarding / concerning | "Regarding the contract, we have three open questions." |
| because | given that / in light of | "In light of the new data, we should reconsider." |
| first / second / third | firstly / secondly / thirdly | "Firstly, we need to align on scope." |
| but | however / nevertheless | "Nevertheless, we must proceed with caution." |
| also | furthermore / moreover | "Furthermore, the cost is prohibitive." |
| though | albeit | "The plan is workable, albeit risky." |
| to (purpose) | in order to / so as to | "In order to maintain quality, we extended the timeline." |
| in spite of | notwithstanding | "Notwithstanding the budget cut, we delivered on time." |
| if you do not / unless | failing that / barring that | "Failing that, we will roll back to v3.4." |
"Notwithstanding the budget cut, we delivered on time. Furthermore, customer satisfaction is up 12%."
Pronunciation tips for tricky words
"ubiquitous" = yoo-BIK-wi-tus
"exacerbate" = ig-ZAS-er-bate
"untenable" = un-TEN-uh-bul
"tantamount" = TAN-tuh-mount
"engender" = en-JEN-der
Common C1/C2 mistakes
- Using "regarding" too often: in formal writing, "regarding" is fine — but if you use it 5 times in one email, it sounds stiff. Mix with "about," "on," or "concerning."
- "Hence" without comma: "The data is incomplete hence we cannot proceed" → "The data is incomplete; hence, we cannot proceed." "Hence" needs a comma after.
- "Nevertheless" vs "however": both contrast, but "nevertheless" is heavier — use sparingly. "However" is the workhorse.
- "In lieu of" overuse: reserve for genuine substitution ("stock options in lieu of bonus"). Do not say "I went to the meeting in lieu of working from home" — odd usage.
- "Compelling" vs "compelled": "compelling" = persuasive ("a compelling argument"). "Compelled" = forced ("I felt compelled to act"). Different meanings.
Practice: Test yourself
Tap each question to reveal the answer.