clear easy to see through, rather than coloured or dirty: 
 The table top is a piece of clear glass.
 The table top is a piece of clear glass.  a clear liquid
 a clear liquid  The water was so clear that you could see down to the bottom of the lake.transparent
 The water was so clear that you could see down to the bottom of the lake.transparent clear - used especially about materials and solid things. 
Transparent is a little more formal than 
clear: 
 Fill a transparent plastic bottle with water.
 Fill a transparent plastic bottle with water.  a piece of transparent film
 a piece of transparent film  Melt 2 ounces of butter in a large frying pan, and cook the onions until they are almost transparent.see-through
 Melt 2 ounces of butter in a large frying pan, and cook the onions until they are almost transparent.see-through made of a very thin material that you can see through - used especially about women’s clothes: 
 She wore a black see-through dress.limpid literary
 She wore a black see-through dress.limpid literary clear - used especially about water or other liquids . This is a very formal word which is used in novels and literature: 
 limpid pools
 limpid pools  She gave her a golden flask of limpid olive oil.opaque
 She gave her a golden flask of limpid olive oil.opaque difficult to see through: 
 The shower has an opaque glass door.
 The shower has an opaque glass door. [TahlilGaran] English Thesaurus ▲