There is a lot of kind of japanese terminologies to define the types of sake, which can be confusing for the uninitiated. 
There are two basic types of sake: Futsū-shu and Tokutei meishō-shu.
Futsū-shu can be considered as table wine and there is no real regulation to make it.
Tokutei meishō-shu refers to premium sakes distinguished by the degree to which the rice has been polished and the added percentage of brewer's alcohol or the absence of such additives.
Junmai 100% pure rice sake without any additives such as ethyl alcohol [often known as brewers alcohol], sugars and starches. Junmai is sake made of rice, water, yeast and kōji mould only.
Junmai ginjo ou ginjo To be classified ginjō the rice grain must be polished down to 60% or less of its original size.
Junmai daiginjo ou daiginjo  To be classified daiginjō the rice grain must be polished down to 50% or less of its original size
Nihonshu ‘Japanese Sake’.  The word ‘Sake’ in Japanese actually refers to all alcoholic beverages, so if you were in Japan and wanted to order what we know  as ‘Sake’ you would actually ask for "Nihonshu".

It is the Rice Polishing Rate. The percentage is telling you how much of the rice grain remains after polishing
"Starter mash" or "moto" It is where the Tōji [master brewer] combines steamed rice, kōji, water and yeast together in quantities suitable to let the yeast multiply and become vigorous.  This active yeast is what will convert the sugar from the rice into alcohol and so needs to be strong when more of the steamed rice, kōji and water are added to create the main mash.  During brewing unwanted microbes can enter the ferment and ruin the brew, so lactic acid needs to be added or created to make the mash acidic enough to kill off any unwanted microbes and allow the yeast to work efficiently.
Kōji It is the steamed rice that has been inoculated with starch-breaking moulds.
Kōji-kin It is a starch-breaking mould with the Latin name ‘Aspergillus Oryzae’ which is added to the rice to produce enzymes to convert the starch in the rice to sugar which can then be converted to alcohol.  The kōji mould coats the rice with a pure fluffy white outer layer that is also highly fragrant.
Kimoto It is one of the most traditional ways for preparing the starter mash, which includes the laborious process of grinding it into a paste. Over the following weeks naturally occuring lactic acid bacteria will enter the mash which will produce the required lactic acid and then yeast will be added.  The total time for a brewing Sake this way is about 4 weeks.
Yamahai It is a simplified version of the kimoto method, dicovered in 1909. Yamahai skips the step of making a paste out of the starter mash. While the yamahai method was originally developed to speed production time, it is slower than the modern method and is now used only in specialty brews for the earthy flavors it produces.With this method the production of the ferment is much easier but still takes roughly 4 weeks.
Sokujō "quick fermentation", the modern method of starter that is most commonly used by breweries today. Lactic acid, produced naturally in the two slower traditional methods, is added to the starter (moto) to inhibit unwanted bacteria. This ferment only takes 2 weeks, compared to about 4 weeks for Kimoto and Yamahai
Muroka It means unfiltered. It refers to sake that has not been carbon filtered, but which has been pressed and separated from the lees, and thus is clear, not cloudy. Carbon filtration can remove desirable flavors and odors as well as bad ones, thus muroka sake has stronger flavors than filtered varieties.
Nigori (Nigorizake) It is a cloudy sake. The sake is passed through a loose mesh to separate it from the mash. It is not filtered thereafter and there is much rice sediment in the bottle. Before serving, the bottle is shaken to mix the sediment and turn the sake white or cloudy.
Nama (Namazake) It is a sake that has not been pasteurized.
Genshu = undiluted.  Many sake are diluted with spring water after brewing to lower the alcohol content from 18-20% down to 14-16%, but genshu means that no extra water has been added.
Koshu Aged Sake.  Many people have the misconception that Sake cannot be aged, but actually this is where it is easy to draw parallels with wine.
Taru (Taruzake) It is sake aged in wooden barrels or bottled in wooden casks. The variety of wood is used Japanese cedar.
Kijōshu ‘Noble-Brew Sake’.  Generally aged before being sold, this type of Sake often has a range of flavours similar to sherry.  There are some similarities in production technique to that of port wine, although the Kijōshu technique has a much longer history.  To make Kijōshu, the Tōji brings the ferment to an early halt by adding a full-bodied Sake from a previous year into the still fermenting batch.
Shiboritate "freshly pressed", refers to sake that has been shipped without the traditional six-month aging/maturation period
Kura  It means Sake Brewery
Kuramoto Owner of the Sake Brewery
Kurabito Sake Brewery workers
Shuzō Sake brewery
Tōji Master Brewer or Head Sake Brewer