Oldster and Oldtimer

Oldster noun - A person of advanced years.

Oldtimer and oldster are semantically related In some cases you can replace term "Oldtimer" with "Oldster", this nouns are similar.

Oldtimer noun - An experienced person who has been through many battles; someone who has given long service.

Oldster and oldtimer are semantically related in older person topic. You can use "Oldster" instead a noun "Oldtimer", if it concerns topics such as senior, someone of advanced years.