Hose are a period item of clothing used for keeping the legs warm. Often made out of a linen or wool. Hose were bias-cut, so if patterned, diagonal stripes and diagonal check or plaids would be most common. Sometimes hose had leather soles sewn on to them, so you didn't have to wear shoes (you can do this to modern socks too). Various devices including garters and attachments to a belt or upper garment (points) were used to stop hose falling down.
During the 14th century and earlier hose would be made of two separate legs. These might be rolled down during hard labour. Later during the 15th century hose became a one piece garment with an attached codpiece. One piece hose were pointed to a doublet or pourpoint. Hose are depicted as tightfitting, so baggy hose are inappropriate.
Hose in Re-Enactment
Hose are typically made of wool although some use a blend to try to get a more elastic fit. Modern hose typically have a sheen to them that indicates modern materials and thus are frowned upon by re-enactors and shunned by living historians.
In Australia there is a perception that hose aren't very blokey and consequently there are few high medieval or renaissance reenactment groups, although this is beginning to change. Conversely, New Zealand men's manliness is full equal to the wearing of hose.
Hose in the SCA
There are some modern hose-like items that can be worn, and look fairly close to period hose.