I

Ibis
Red ibis feathers are used for tail fibres. Substitutes are now used, ex: feathers dyed red.

Ice Chenill
Another plastic chenille material. Stiffer than Estaz, some nice colors, but not as high quality as Estaz. A good substitute.

Improved clinch knot
A popular knot used to tie the tippet to the fly. It is formed by threading the hook eye with the tippet, wrapping the tag end of the tippet around the standing part, and then sliding the tag end through an open loop formed near the hook eye and then tightened. It is a very strong knot and reduces the chances of a fish stealing the fly.

Index finger grip
A particular way to hold the fly rod with the casting hand. This grip is best for most newcomers. Placing the index finger of the casting hand on top of the fly rod handle leads to precise control and accuracy in the cast. After getting comfortable with the basic casting motion, newcomers can then progress to the thumb-on-top grip.

Inlet
The area where a stream flows into a lake, pond or ocean.

Interlocking loops
The connection formed by union of two lines each with a loop in the end; functional for connecting leaders, tippets, lines, etc. (also called "handshake loop")