I think (that)

1. have an opinion. = meddwl (stem: meddyli-), credu (South).

what do you think about it? = beth dych chi'n ºfeddwl amdani?
I think it is unfair = dw i'n meddwl bod hi ºddim yn ºdeg.
-Will they come? -I don't think so: ºddôn nhw? - dw i ºddim yn meddwl.

2. reflect, cogitate. = meddwl (stem: meddyli-).

think before answering = meddyliwch cyn ateb.
to think of someone = meddwl amº rywun.
to think about doing something = meddwl am ºwneud rhywbeth.
to think again (have second thoughts) = ailfeddwl.

(to quote someone's thoughts, use the preterite meddyliod; but generally "thought (that)" is translated by the imperfect):

"It is too late," thought Aled = "Mae'n rhy hwyr," meddyliod Aled.
He thought that Wales won yesterday = roedd e'n meddwl mai Cymru erillodd ddoe.

---

1. believe. = 思う（おもう）、考える（かんがえる）。　
I think that she is honest = 彼女は正直（しょうじき）だとおもいます。
I don't think that's fair on you = それではあなたがかわいそうだと思う。
Do you think that he will pass the exam? = 彼は試験(しけん）に合格（ごうかく）すると思いますか。
Yes, I think so = ええ、そうおもうます。
No, I don't think so = いや、そうは思いません。
Where do you think he is is from? = 彼はどこの出身（しゅっしん）だと思いますか。
What do you think has happened? = 何が起（お）こったと思いますか。

２．cogitate. = 考える（かんがえる）、熟考（じゅくこう）する。
To think in Japanese = 日本語で考える。
Think carefully before you decide = 決める前によく考えなさい。
Let me think = 考えさせて下さい。
What are you thinking about? = 何を考えているの？
I'll think about it = 考えておきましょう。
I'm thinking about studying abroad = 留学することを考えています。
I thought of my family = 家族の事を考えた。
She is thinking of changing her job = 彼女は転職を考えている。
I've never thought of it = そんあ事は考えたこともない。
Let me think it over again = それをもう一度よくか考えさせてください。

Informal/Casual form + to omou
(I think ～)

Eg.
Verb: Kare ga konai to omoimasu.
(I think that he won't be coming.)

i-adjective: Nihongo wa muzukashii to omoimasu.
(I think/find that Japanese is difficult.)

na-adjective: Kyou no TESUTO wa kantan da to omoimasu.
(I think that the test today will be easy.)

Noun: Ano hito wa nihonjin da to omoimasu.
(I think that person over there is a Japanese.)



---そこでしようと思う (Soko de shiyou to omou)---

This only applies to verbs:

Volitional-form + to omou
(I plan to/think of ～)

Eg.
Ashita eiga ni ikou to omoimasu.
(I plan to go for a movie tomorrow.)

Kono PASOKON wo kaou to omoimasu.
(I plan to buy this computer.)

So, how do we say "I plan to go shopping tomorrow" & "My sister plans to go shopping tomorrow"?

1)
(Watashi wa) Ashita kaimono ni ikou to omoimasu.

2)
Imouto wa ashita kaimono ni ikou to omoimasu. ----- Incorrect
Imouto wa ashita kaimono ni ikou to omotteimasu. ----- Correct

When saying someone else's thought, "omotteiru" is used instead of "omou".

---------------------------------------------------------------------------------------

Next, what's the difference between the following 2 sentences?

1) Raishuu PAATII wo yarou to omoimasu.
2) Raishuu PAATII wo yarou to omotteimasu.

The 1st sentence would mean "I plan to have a party next week". Whereas the 2nd sentence would mean "I have been planning of having a party next week".

When "omotteiru" is used on the speaker himself/herself, it means that the speaker has been thinking about something for a long period of time. 

「そう思う」 can be used with nouns/adjectives/verbs. On the other hand, 「そうだと思う」 can only be used with nouns/na-adjectives.

Eg.
A:「このドレス、有名ブランド品よね／かなり高いよね／私に似合うよね」
B:「私もそう思う」

A:「このドレス、有名ブランド品よね」
B:「私もそうだと思う」

Then again, 「そうだと思う」 can also be used with i-adjectives and verbs, isn't it?

Eg.
A:「ねぇ、私ってかわいい？」
B:「ああ、そうだと思うよ」

Strictly speaking, it can only be used with nouns or na-adjectives (which have the same characteristic as nouns). Although the above example is grammatically incorrect, it is commonly used in that manner.

Perhaps, it is understood that 「の」 is added to the sentence to normalize it.

Eg.
A:「ねぇ、私ってかわいい（の）？」
B:「ああ、そうだと思うよ」

A:「山田さんは行く（の）？」
B:「そうだと思う」

(source)

---

Mitä mieltä olet + sta, stä : what is your opinion about...
Mitä tykkäät + sta, stä : what do you think about...

Minusta / Minun mielestä : In my opinion...



Olen samaa mielta (kuin sinä) : I agree (with you).
Olen eri mieltä : I disagree.
Oletko sita mielta? : Do you (really) think so?

minä -> minusta
sinä -> sinusta
hän -> hänestä



me -> meistä
te -> teistä
he -> heistä

tämä -> tästä
tuo -> tuosta
se -> siitä

- Mita mielta sina olet Liisasta?
- Minusta Liisa on ihan okei. Kiva tyttö.
- Jaa? Minun mielesta hän on vähän omituinen.

- Mita tykkaät Helsingistä?
- Minusta Helsinki on aika kiva kaupunki, ainakin kesällä.

Agreeing with someone's opinion can also be expressed by simple niin 'quite so' or niin + the verb (niin on, niin puhuu).

- Tänään on kiva ilma.
- Niin on. Olen samaa mielta kuin sina.

- Marcel puhuu Suomea oikein hyvin.
- Niin puhuu.

- Minusta täällä on tylsaa. Mita mielta sina olet?
- No jaa. Minusta täällä on aika kivaa. Sinun mielesta kaikki on aina tylsää.

- Tämä on kiva disko.
- Oletko sita mielta? Minä olen eri mielta. Minusta tämä on ihan tylsä paikka,
ja kalliskin!

The suffix han, hän is used a lot, especially in questions, where it usually means
'I wonder (whether)'.

Onkohan hän suomalainen? I wonder whether he is Finnish?
Mikähän tamä on? I wonder what this is?

- Kuule, puhu~ikohan Miguel suomea?
- Ei kai. Miguel on espanjalainen.

- Piihuukohan Joel englantia?
- Ehkä. Voi olla. En ole varma.

- Onkohan tuo mies suomalainen?
- Kylla kai. Luultavasti.

- Onkohan Miguel espanjalainen vai portugalilainen?
- Varmaankin espanjalainen. Hän puhuu espanjaa.

Kuule : listen.
Ei kai : probably not, I don't think so.
Ehkä : maybe.
Voi olla : maybe.
Varma : sure.
Kylla kai : probably yes, I think so.
Luultavasti : probably, I think so.
Vai : or (in questions).
Varmaankin : probably, most likely.

raicaa (1)
This verb is used to express possibiity or probability:
Taidan olla sairas : I'm probably ill, I think I'm ill.
Hän taitaa olla myöhässä : He seems to be late.
Hän ei taida tulla : He's not likely to come. He doesn't seem to be coming.