in and out movement (esp. during intercourse); pistoning
extraction; abstraction; selection (from a group); sampling
lottery; raffle; drawing (of lots)
abstractness; abstraction
abstract concept; abstraction; abstract idea
sampling (i.e. as a survey method)
abstract painting; abstract art
abstract expressionism (art movement)
abstract human labour; abstract human labor
abstract algebra; modern algebra
self-extracting (computer file)
extractor mark (on a cartridge)
abstract testing methodology
message-submission abstract-operation
Summarize abstract-operation