Namazake (生酒) is sake that has not been pasteurized.
It requires refrigerated storage and has a shorter shelf-life than pasteurized sake.

Genshu (原酒) is undiluted sake.
Most sake is diluted with water after brewing to lower the alcohol content from 18–20% down to 14–16%, but genshu is not.

Muroka (無濾過) 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.

Nigorizake (濁り酒) is 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.

Seishu (清酒), "clear/clean sake", is the Japanese legal definition of sake and refers to sake in which the solids have been strained out, leaving clear liquid.
 Thus nigorizake and doburoku (see below) are not seishu and therefore are not actually sake under Japanese law.
Nigorizake can receive the seishu status by being strained clear and having the lees put back in afterward.

Koshu (古酒) is "aged sake".
Most sake does not age well, but this specially made type can age for decades, turning yellow and acquiring a honeyed flavor.

Taruzake (樽酒) is sake aged in wooden barrels or bottled in wooden casks.
The wood used is Cryptomeria (杉, sugi), which is also known as Japanese cedar.
Sake casks are often tapped ceremonially for the opening of buildings, businesses, parties, etc.
Because the wood imparts a strong flavor, premium sake is rarely used for this type.

Shiboritate (搾立て), "freshly pressed", refers to sake that has been shipped without the traditional six-month aging/maturation period.
 The result is usually a more acidic, "greener" sake.

Fukurozuri (袋吊り) is a method of separating sake from the lees without external pressure by hanging the mash in bags and allowing the liquid to drip out under its own weight.
Sake produced this way is sometimes called shizukuzake (雫酒), meaning "drip sake".

Tobingakoi (斗瓶囲い) is sake pressed into 18-liter (4.0 imp gal; 4.8 U.S. gal) bottles ("tobin") with the brewer selecting the best sake of the batch for shipping.
Namazake (生酒) is sake that has not been pasteurized. It requires refrigerated storage and has a shorter shelf-life than pasteurized sake.
Genshu (原酒) is undiluted sake. Most sake is diluted with water after brewing to lower the alcohol content from 18–20% down to 14–16%, but genshu is not.
Muroka (無濾過) 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.
Nigorizake (濁り酒) is 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.
Seishu (清酒), "clear/clean sake", is the Japanese legal definition of sake and refers to sake in which the solids have been strained out, leaving clear liquid.  Thus nigorizake and doburoku (see below) are not seishu and therefore are not actually sake under Japanese law. Nigorizake can receive the seishu status by being strained clear and having the lees put back in afterward.
Koshu (古酒) is "aged sake". Most sake does not age well, but this specially made type can age for decades, turning yellow and acquiring a honeyed flavor.
Taruzake (樽酒) is sake aged in wooden barrels or bottled in wooden casks. The wood used is Cryptomeria (杉, sugi), which is also known as Japanese cedar. Sake casks are often tapped ceremonially for the opening of buildings, businesses, parties, etc. Because the wood imparts a strong flavor, premium sake is rarely used for this type.
Shiboritate (搾立て), "freshly pressed", refers to sake that has been shipped without the traditional six-month aging/maturation period.  The result is usually a more acidic, "greener" sake.
Fukurozuri (袋吊り) is a method of separating sake from the lees without external pressure by hanging the mash in bags and allowing the liquid to drip out under its own weight. Sake produced this way is sometimes called shizukuzake (雫酒), meaning "drip sake".
Tobingakoi (斗瓶囲い) is sake pressed into 18-liter (4.0 imp gal; 4.8 U.S. gal) bottles ("tobin") with the brewer selecting the best sake of the batch for shipping.
Sake