～そうです（様態）

How it works

This そう attaches to the stem of a verb or adjective and says what something looks like from where you stand: an impression from sight, sound or touch, formed before you have checked. Grammatically it is a な-adjective, so it takes な before a noun (おいしそうなケーキ) and に before a verb (眠そうに話す).

With verbs: about to happen, likely to happen

ます-stem + そう: 降りそう (looks like rain), 落ちそう (about to fall), 泣きそう (about to cry). With verbs that describe an outcome rather than a moment, it means a likely result: 間に合いそう (looks like we will make it), できそう (looks doable).

With adjectives: looks, seems

Drop the final い: おいしい → おいしそう, 難しい → 難しそう. な-adjectives use the bare stem: 元気そう, 大変そう, 暇そう. Two irregulars: いい → よさそう and ない → なさそう (お金がなさそう, つまらなさそう).

Negatives

Verbs: 降りそうもない／降りそうにない (no sign of rain). い-adjectives: おいしくなさそう (looks bad) or おいしそうじゃない (does not look good); な-adjectives: 元気じゃなさそう or 元気そうじゃない. In speech, the ない-form + そう (来なそう, colloquially also 来なさそう) is common for an event that looks unlikely.

It never attaches to nouns; use のようだ／みたいだ for 'looks like a…'. It also sounds odd with qualities you can see outright (color, beauty, size): きれいそう and 赤そう are not natural, because そう is for what you infer, not what you plainly see.

Examples

• この料理、おいしそうですね。 — この りょうり、おいしそう です ね。 — This dish looks delicious.
• 雨が降りそうだから、傘を持って行こう。 — あめ が ふりそう だ から、かさ を もって いこう。 — It looks like rain, so let's take an umbrella.
• 田中さんは今日、眠そうですね。 — たなかさん は きょう、ねむそう です ね。 — Tanaka looks sleepy today.
• この本は難しそうだけど、面白そうだ。 — この ほん は むずかしそう だ けど、おもしろそう だ。 — This book looks hard but interesting.
• 棚から荷物が落ちそうですよ。 — たな から にもつ が おちそう です よ。 — Those things look like they are about to fall off the shelf.
• その仕事は大変そうだけど、給料はよさそうだね。 — その しごと は たいへんそう だ けど、きゅうりょう は よさそう だ ね。 — That job seems tough, but the pay looks good.

Compare with

• Hearsay そうです attaches to the plain form, not the stem: 降りそう (looks like rain) vs 降るそう (I hear it will rain); おいしそう vs おいしいそう. One い changes the meaning.
• ようだ・みたいだ is a judgment from evidence you have weighed, and it works with nouns: 風邪のようだ. そう is the instant impression: 具合が悪そう.
• らしい passes along what you heard with some inference; appearance そう is what you see with your own eyes.

Traps for Spanish, English and French speakers

• Spanish 'parece un médico', French 'il a l'air d'un médecin' and English 'looks like a doctor' all take a noun, so learners produce 医者そうです. Appearance そう never attaches to nouns: 医者のようです or 医者みたいです.
• Thinking 'it looks like it will rain' is 降る + そう, English and Spanish speakers say 雨が降るそうです, which means 'I hear it will rain'. Appearance needs the stem: 雨が降りそうです; likewise おいしそう, never おいしいそう.
• The two irregulars get regularised into 天気がいそう and 時間がないそう (the second is hearsay: 'I hear there is no time'). Say よさそう and なさそう: この店はよさそうだ, 時間がなさそうだ.
• English 'she looks pretty' and Spanish 'se ve bonita' tempt learners into きれいそう, but beauty is seen directly, not inferred, so it sounds odd. Use きれいですね, and keep そう for what you cannot see outright: おいしそう, 難しそう, 楽しそう.