Exceptions are
(a) Combinations with proper names or adjectives derived therefrom, and long or unusual compounds;
| ante-bellum | sister-university | |
| anti-license | post-revolutionary | |
| anti-security | pre-Raphaelite | |
| demi-relievo | re-tammanize |
(b) Words in which the omission of the hyphen would alter the sense;
| re-formation | reformation | |
| re-cover | recover | |
| re-creation | recreation |
17. The negative prefixes un, in, il, im, and a do not take a hyphen except in very rare or artificial combinations; unmanly, invisible, illimitable, impenetrable, asymmetrical.
The negative prefix non calls for a hyphen except in very common words;
| non-existent | non-combatant | |
| non-interference | nonsense | |
| non-unionist | nonessential |
18. The prefixes quasi, extra, supra, ultra, and pan call for a hyphen;
| quasi-historical | supra-normal | |
| quasi-corporation | ultra-conservative | |
| extra-mural | Pan-Germanism |