ASIC stands for Application Specific Integrated Circuit. Basically it is a chip which is optimized to do one task, in the context of this discussion mining cryptocurrencies. Usually it is only small semiconductor companies who are interested in designing and manufacturing ASIC products. The larger semiconductor companies (e.g. Nvidia) usually find the business case for ASIC products not compelling enough to invest in it.
ETH stands for Ethereum, which is a specific cryptocurrency (another example is Bitcoin, abbreviated to BTC). I am not sure what
@tsznecki refers to with abbreviation POS (point of sale?).