Courtine is a posh word for wall or curtain wall - what they 'linked' the gun bastions up with.
Yep lunette means little moon - a fletch is another word for it. Inverted V or half moon shaped outer defences for gates etc - usually on ground level where as gun bastions were normally raised up a bit. With IO's permission I shall paste his summary here for all. If anyone has the osprey ecw fortifications book, you can see exmples in there.
There was a lunette at The Alamo in texas - here's a pic of the model version I built (definitely not tyw/ecw):
Some more info donated by Invisible Officer: yes, the Kurtine (Courtine / Courtain) is the part of the wall between two bastions. The Ravelin (also Wallschild or Schweinekopf) is an outwork that is used to protect the Kurtine It had no permanent connection to the Kurtine, if it has one it is called a Bastei in German fortification. There are those who served only as a protection of the Kurtine against artillery (and giving flanking fire to the bastions) and the more interesting that protect the gates. In these there is a gate in one of the front walls and a drawbridge to the main gate in the Kurtine. Simpler ones are situated on the glacis, not in the Graben. These are named Brückenkopf. The Ravelin is open in the back, so an attacker will wind no cover in it. The most simple is the Flesche (Fleche /"arrowhead" ) , just an inverted V. Later the Lünette (small moon) became more popular , it has the V form with another flank added on the side, giving more oportunity for flanking fire.
If you can get a copy of Eduard Wagner Tracht Wehr und Waffen im Dreissigjährigen Krieg you will find many ideas for TYW fortification models. In 17th century Germany the Kurtine had often trees on top, the roots adding strength to the earthen core. (And looking nice) Windmills are no rare sight on them. On the bastion you will find the Kavalier / Kanonenturm, a raised gum position to give more range for counter battery work.
Here in Berlin we have the Zitadelle Spandau, a small fortress that show most of the 16th century features.
Thanks again IO
VIRTUTIS GLORIA MERCES -- Glory is the reward of valour.