Atomic
adj.
Atomic refers to the specificity of a task. An atomic task is a task that must be completed as soon as it is started.
It helps to reduce all future tasks to the atomic level. Rather than the objective of "write my paper," a student should create several atomic tasks like "check out Book X from the library" and subsequently "select 3 quotes out of Book X."
This draws from Getting Things Done and the 4-Hour Work Week.

