noun

• (agriculture, countable) A process of soil compaction that serves to break up clods and level a field.
  "ploughings and ladderings"
• (uncountable) An interview technique developed in the 1960s in which the interviewer systematically drills down for greater detail at each step.
  "With upward laddering like this, you're going from the bottom of the hierarchy up towards the top, and what you'll typically find is that as you go up the number of branches decreases, so you'll keep hitting the same responses and the same high level goals and values eventually, more or less regardless of where you started from."
• (uncountable) An investment strategy where the investment is spread over multiple bonds or term deposits with rolling maturity dates.
• (uncountable) A regular pattern of oligonucleotide sizes on electrophoretic gels, resulting from the fragmentation of DNA strands during cell death.
  "For example, tobacco cell cultures grown at 5oC, resulted in a loss of viability relative to control cells and exhibited DNA laddering (Koukalova et al., 1997)."