Rigor = secondary school class rigor

Rank = class rank

Tests = standardized tests

Recs = recommendation letters

ECs = extracurriculars

Talent = talent/ability (not exactly sure what this one refers to)

PQs = personal qualities

1st gen = you are a first generation student if your parents didn't go to college

Geo Res = geographical residence

State Res = state residence

Ethnicity = race/ethnicity

Vol Exp = volunteering experience

Work Exp = work experience

Interest = demonstrated interest

(source: reddit)