Kush meaning in sanskrit is Sharp = pointed Puraan say that it was formed when the hairs on Koorm Avataar were loosened during the churning of Ocean and got washed away to the shore and became as Kush grass. read more
First of all , Lord Ram did not name his son. According to Ramayana, Ma Sita was banished from the kingdom of Ayodhya by Lord Rama due to the gossip of his subjects. read more
That same chapter then goes on to describe how the two sons get the name of Lava and Kusha. After the birth of the sons, the disciples there informed Valmiki of this and told to protect the new born children from ghosts and demons. read more