Lethologica: The inability to remember a word or put your finger on the right word
Wikipedia describes the word as a psychological disorder that inhibits an individual's ability to articulate his or her thoughts by temporarily forgetting key words, phrases or names in conversation.
The causes of lethologica include stress, physical fitness, social interaction and memory capacity. It can be categorized as a lifestyle disease which is affected by individual personality traits.
Lethologica was suggested by redmicasupra you can see his blog @ http://w17l.blogspot.com/