Parallelism (commonly used term in NTB negotiations under NAMA): Means that NTBs should be addressed together with, or parallel to reduction in tariffs. 

Peace clause: Article 13 of the Agreement on Agriculture protects certain countries using certain subsidies from being challenged under the WTO agreement and/or countervailing measures. It expired in 2003.

Preferential access: Special treatment for least developed countries in developed countries’ markets.

Preference erosion: Loss of preferential treatment that least developed countries get in developed countries’ markets.