going, journey, carry out, conduct, act, line, row, bank
行 centers on movement along a path: going, journeying, or carrying out an action. The line/row/bank senses extend this idea to things arranged along a course.
to go; to move (towards); to head (towards); to leave (for)
to perform; to do; to conduct oneself; to carry out
action; conduct; behaviour; behavior; mobilization; mobilisation
bank; banking institution
act; deed; conduct
travel; trip; journey; excursion; tour
execution (e.g. of a plan); carrying out; (putting into) practice; action; implementation; fulfillment; realization
line (of text); row; verse
publication (of a newspaper, magazine, book, etc.); issue
executive; government
moving forward (e.g. of a vehicle); onward movement
fashion; trend; vogue; craze; fad; popularity
transition; changeover; switchover; shift
flight; flying; aviation
airplane; aeroplane; plane; aircraft
going ahead; going first
running (of a car, bus, etc.); traveling; travelling
(one's) whereabouts
execution; carrying out; performance; enforcement; exercise; service; conduct
acting as agent; acting on (someone's) behalf; executing business for
training; practice; discipline; study
to be popular; to come into fashion
accompanying (someone); going with; travelling together
present; current; in operation
行 is a pictograph of a crossroads or intersection, representing movement and paths. The modern form preserves the left and right halves as 彳 and 亍, which together suggest stepping or going.
The left side 彳 looks like a step, and the right side 亍 looks like another step. Together they form a path: going, journeying, or carrying out an action along a line.
For コウ, imagine a long line of people going on a journey, all carrying a single コウ (こう, incense stick) to mark the path: こう -> コウ.