1.
of hair: lack of a tendency to curl
2.
freedom from crooks or curves or bends or angles
3.
trueness of course toward a goal
4.
having honest intentions
5.
a sexual attraction to (or sexual relations with) persons of the opposite sex
The following are synonyms for 'straightness'. Click on any of them to get both Bibliodata's full list of common definitions and a further set of synonyms.
During World War II, Russians used dogs strapped with explosives to blow up German tanks. They trained the dogs to associate the tanks with food and ended up destroying about 25 German tanks using this method.