网易公开课VOA短语系列about leatherneck or

• leatherneck海军陆战队
• grunt咕囔

which do not sound like nice names to call somebody

• dough boy 步兵（一战）the solders who fought for world war I
• Gi or Gi Joe特种兵（二战）

other meanings,such as clothes,weapons and equipment.
other meanings like organize or clean

• we GI'd an area means we occupied the area.

• the area is GI.means the area is good.

• GI also means poor work or something badly done.

• GI comes from galvanized iron. a material produced for special strength.

• grunt.comes from the sound when the troops carrying heavy equipment.

• leather 皮革

• leatherneck.

to protect them from cuts during battles or the sun burned the Marin's necks until their skin looked like leather.

• marine.

related to the sea. 海军陆战队