I feel like I'm outdated when 昭和/shouwa is used as a certain meaning.

There are traditional Japanese era names in Japan. We use both Western/Christian year and the traditional Japanese year. For example, this year is 2011 and 平成23年/heisei 23 nen (年 means year). 平成/ heisei is the current era name. Every time a new emperor (天皇/ tennou in Japanese) ascends the throne, a new era begins and a new era name starts being used. So, 平成23年 indicates that it's been 23 years since the current emperor ascended the throne. Actually, I don't know exactly how the era names are decided.

I still remember the time when 平成/heisei was announced as a new era name 23 years ago (please see the YouTube video). According to the announcement, 平成/heisei comes both from 内平外成 written in 史記, a well-known old Chinese book written by 司馬遷 in the Early Han /前漢時代, and from 地平天成 written in 書経, a very old Chinese book. If I make it short, 平成/heisei was named in hopes for an era of peace. Specifically, it was hoped that Japan would be well and peacefully governed while keeping good relationships with other countries. I don't think that people know that, but they assume that 平indicates 平和(heiwa, peace in English), and 成 indicates 成る(naru/ accomplish etc.in English).

I often hear people, especially young ones, saying that 昭和な感じがする. The literal translation of the Japanese phrase is that I feel that it is 昭和/shouwa , but the meaning is that I feel that it is old or outdated. 昭和/showa is the previous era name before 平成/heisei. Since 昭和/showa was used from 1926 to 1989, 昭和/showa seems to sound like former times to young people. Because of this, 昭和/showa is often used to indicate "old" and "outdated". Every time I notice that 昭和/showa is used as the meaning of them, I feel like I'm outdated since I'm familiar with 昭和/showa.