まるっきり・丸っきり・丸っ切りmarukkiri[0]heiban (flat)

1. adverbcompletely; absolutely; totally; (not) at all
   おもってたのとまるっきり違ちがいますねえ。↗

   It's really different from what I expected.

• SynonymまったくNeutralThe most versatile of these: fits affirmatives and negatives alike, and can even be an exclamation (「全く、もう」). 丸っきり is more colloquial and usually takes a negative.
• SynonymすっかりNeutralMostly in affirmative sentences, for a state changing completely, as in 「すっかり忘れた」. 丸っきり typically goes with negatives.
• Synonym完全かんぜんNeutralA na-adjective; it modifies verbs as 「完全に」, as in 「完全に理解した」, and leans formal. 丸っきり is colloquial and usually takes a negative.
• Synonym全然ぜんぜんCasualThe everyday colloquial favorite, usually with a negative, as in 「全然分からない」. Largely interchangeable with 丸っきり, and more common.
• Synonym皆目かいもくWrittenA written/formal word, almost always with a negative; classic in 「皆目見当がつかない」. In speech you would say 「全然」 or 「丸っきり」.
• Synonym一切いっさいNeutralWith a negative it means flatly none whatsoever, as in 「一切関係ない」, with a categorical tone; also a noun meaning everything.
• SynonymさっぱりNeutralWith a negative it means not at all, as in 「さっぱり分からない」; it also means refreshed or neat, senses 丸っきり lacks.
• SynonymすべてNeutralMeans everything or all, stressing scope, as in 「全て終わった」; it is not used to intensify a negative, unlike 丸っきり.
• Synonym一向いっこうWrittenUsually as 「一向に」 with a negative, as in 「一向に構わない」; written in flavor and more solemn than 丸っきり.
• Synonym何もなにもNeutralWith a negative it means nothing at all, as in 「何も知らない」 — the point is the total absence of the object; 丸っきり stresses degree.
• SynonymからっきしCasualColloquial, usually with a negative, often about being hopeless at something, as in 「酒はからっきしだ」. 丸っきり is not limited to ability.
• Synonym万々まんまんWrittenOld-fashioned written word meaning fully, amply; with a negative, never. Everyday language uses 「決して」 or 「十分」 instead.
• Related絶対にぜったいにNeutralStresses that something holds no matter what — resolve or strong conviction, as in 「絶対に壊れない」. 丸っきり is about thoroughness of degree.
• RelatedまるでNeutralMainly a simile marker — just like, as in 「まるで夢のようだ」; with a negative it comes close to 丸っきり.
• RelatedおよそWrittenMainly about, roughly, on the whole; only with a negative or negative-flavored word does it mean utterly, as in 「およそ無理だ」. Written in flavor.
• RelatedまんざらNeutralMostly in 「まんざらでもない」, meaning not altogether bad — a soft, hedged tone, the opposite of 丸っきり's thoroughness.
• RelatedとんとWrittenSomewhat dated, usually with a negative, as in 「とんと見かけない」; it can also mean completely. Everyday speech prefers 「全然」.
• RelatedきれいさっぱりCasualColloquial, for wiping something out cleanly and completely, as in 「きれいさっぱり忘れた」; used in affirmative sentences.
• RelatedおおよそWrittenPrimarily roughly, approximately — an estimate word, as in 「おおよその見当」; the completely sense appears only with a negative. Written in flavor.
• Antonym少しすこしNeutralA little, a small amount or degree, as in 「少し分かる」 — the opposite of 丸っきり's completeness and thoroughness.
• AntonymややWrittenWritten in flavor; slightly, somewhat, as in 「やや大きい」 — the opposite of 丸っきり's totality.

For colloquial 'not at all' or 'completely', use 「丸っきり」, as in 「まるっきり分からない」. 「全然」 is the most common everyday choice and largely interchangeable; 「全く」 fits both speech and writing; for a state changing completely, say 「すっかり」. Formal prose offers 「皆目」「一向」「頓と」; 「からっきし」 is colloquial for total inability; 「一切」 is categorical; 「丸で」 mainly marks similes; 「絶対に」 stresses conviction; 「全て」 stresses scope; 「何も」 stresses absence; 「まんざら」 is a softener; 「およそ」「おおよそ」 mean roughly; 「万々」 is dated; antonyms 「少し」「やや」 mean a little.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. （下したに打ち消うちけしの語ごを伴ともない）全然ぜんぜん。まったく。まるきり。