In Aikido, different dojos seem to latch on to using either dori or tori when describing grabbing attacks. For instance one dojo might say:
Katate Dori
Another would say:
Katate Tori
Each dojo will profess that their way of saying / spelling it is the more traditional and correct. Is there a difference between these two similar terms, and if so which one is more correct for denoting a grab?
I know very little about Aikido and can only explain general facts about the Japanese language.
“Tori” and “dori” in these example are the noun form of the verb toru (取る; take, grab). In isolation, this noun form is read as “tori.”
Both Katate Tori and Katate Dori are compound words made of katate (片手; one hand) and tori. However, in Japanese, the first consonant of the second component of a compound word is often changed as k→g, s→z, t→d and h→b. This phenomenon is called rendaku (連濁). Note that I said “often,” not “always.” If rendaku occurs in your case, the compound word becomes Katate Dori. If not, it becomes Katate Tori.
There are some patterns when rendaku tends to occur and when it cannot occur as is explained in Wikipedia, but there is no absolute rule that explains everything. In the case of katate + tori, it is certainly possible to have rendaku here, so Katate Dori is a possible form. But this does not mean that rendaku must occur, so the form Katate Tori is also possible.
Often only one form survives and the other form dies out, in which case we can say that one form is correct and the other is incorrect in the modern language. In some cases, the version without rendaku and the version with rendaku both survive but mean different things. For example, both yamakawa and yamagawa are compound words made of yama (山; mountain) and kawa (川; river), but yamakawa means mountains and rivers whereas yamagawa means a river in a mountain.
But in your case, it seems that both forms are used in the same way judging from several webpages in English I found by web search. (I checked the pages in English because it is difficult to search this in Japanese, because when written in Japanese, both become 片手取り, as Andrew stated in his answer.) From this, I see no evidence that one is “more correct” than the other, whatever “more correct” means.
巻き寿司 as "maki sushi", and similar people.
The Japanese Wikipedia page for Aikido refers to the term as 片手取り, but doesn't give any information on how the word is read. The word also doesn't appear to show up in the dictionary.
So, essentially, there is a possibility that the ending is read -どり rather than -とり. A quick Google search brings up one or two results that explicitly say it's read as かたてどり, but nothing definitive. It seems clear, however, that there is no difference between かたてどり and かたてとり besides the one character in its spelling.
In my opinion, it would be read "dori", as it happens a lot in Japanese that consonants become voiced when used as a suffix like this.
Looking at goo.ne.jp's dictionary (based off 大辞泉):
１ 手の中におさめる。手に持つ。
Source: http://dictionary.goo.ne.jp/leaf/jn2/161480/m0u/%E5%8F%96%E3%82%8B/
With the last part of the definition meaning to hold in one's hand. This matches more closes with the definition of denoting a grab that you are referring to. I was not able to find どり denoting the same meaning, only a usage meant for the indication of volume:
（「…どり」の形で、数量を表す語に付けて用いる）
Source: http://dictionary.goo.ne.jp/leaf/jn2/160951/m0u/
I've also confirmed this in 大辞林, which lists definition 1 as:
手に持つ。
"Hold in hand"
Tori and Dori are the same word. Because Dori is the voiced version of Tori, to a Japanese speaker there would be no perceived difference. However, katate dori would probably be easier to be spoken for a native speaker and thus would appear that they may be the more correct answer.
another more famous example of this is when you combine Ao and Sora together you get AoZora.
If its talking about strength then my opinion would be that どり would be a better choice than とり. The reason for this is because just like ペラペラ (fluent) ベラべラ (chatter) ころころ (the sound of something rolling) ごろごろ( a louder sound of something rolling) and so forth tend to become voiced when its talking about exaggeration or strength. Another example ザザ (the sound of heavy rain). Where とり just sounds weaker in context in general. Any flaws to my theory?
