horse chestnut. n. 1. Any of several trees of the genus Aesculus, especially the European species A. hippocastanum, having opposite, palmately compound leaves, erect clusters of white flowers tinged with red or yellow, and spiny or smooth capsules containing large shiny brown seeds.
Painful erections are very uncommon unless you have recently experienced penile trauma or irritation. Other causes of erectile pain would include: 1  Peyronie's disease. 2  Penile mass. 3  Priapism. 4  Phimosis. 5  Penile Injury.
1 Psychological conditions, such as stress, anxiety or depression. 2  Drug and alcohol use, especially if you're a long-term drug user or heavy drinker. 3  Prolonged bicycling, which can compress nerves and affect blood flow to the penis, may lead to temporary or permanent erectile dysfunction. 4  Causes.