1. barrier= anything that prevents progress or makes it difficult for someone to achieve something

These regulations would place barriers in the way of genetic research.

a barrier to: Disability need not be a barrier to a successful career.

High levels of debt are a major barrier to economic development.

2. experiment N./ V.= to try new ideas, methods, or activities in order to find out what results they will have

E.G. a designer who is not afraid to experiment 

e.g. experiment with: She likes experimenting with different hairstyles.

3. index= an alphabetical list of something such as subjects or names at the back of a book, that shows on which page they are mentioned

e.g. Look up the term you want in the index.

4. integrate= to make someone become a full member of a group or society and be involved completely in its activities

e.g. integrate someone into something: Science is integrated with technical support.

5. sufficient= as much as is needed

e.g. sufficient time/resources/information

e.g. sufficient for: Bedside lighting alone is not sufficient for most bedrooms.

sufficient to do something: There is now sufficient evidence to prove his claims.