before, ahead, previous, future, precedence
先 centers on being ahead in time or order: before, previous, or taking precedence. The sense of 'future' is a natural extension, as what lies ahead is yet to come.
先 is thought to combine 之 (footprint, advance) with 儿 (person), suggesting a person stepping forward or going ahead. The modern form retains the idea of precedence.
The top part looks like a foot stepping forward, and the bottom 儿 is a person. Picture someone taking the first step ahead of others: 先 means before or ahead.
For セン, imagine a centipede racing ahead, its many legs always one step before the rest: cent -> セン, and it's always in front.
point; tip; end; nozzle
teacher; instructor; master
first (of all); firstly; to begin with; before anything else
preference; priority; precedence; right of way
senior (at school, work, etc.); superior; elder; older person; predecessor
the other day; a few days ago
going ahead; going first
last week; the week before
last month
advanced; developed
head (of a line, group, etc.); front; lead; forefront; vanguard
pointed end; tip; point; cusp (of a leaf, crescent moon, etc.); apex (of a curve)
starting in advance; starting first; going first; going ahead
ancestor; forefather; foremother
head start; initiative; preemption
cutting edge; leading edge; forefront; state of the art
the head; the foremost; beginning; the very front
ancestor
for now; for the time being; for the present
fingertip; finger
arriving first
to do (something) before (something or someone else); to be ahead of (others, the times, etc.)
previous generation (of a family); previous head of the family; one's (late) father
moving first; person with the first move
futures; futures contract
a short while ago; a moment ago; just now; some time ago
before; previously
toes; tips of the toes; toe of a shoe, sock, etc.
guidance; leadership; leading the way
destination
receiving in advance (e.g. wages, interest); taking before others
putting off (doing); postponement; delaying
forerunner; precursor; pioneer; leader
arrowhead
preconception; preconceived notion; prejudice
distant future; inevitable future
pioneer; leader; taking the initiative; forerunner; harbinger; herald
predecessor; pioneer; ancestor
taking the initiative
before one's eyes; under one's nose
lip service; mere words; professions
destination; place one stays during a trip
the future; future prospects
other party; other side
foresight; anticipation
address; destination
beginning of spring
place of work
precedent
inborn; innate; inherent; congenital; hereditary
point of a spear; spearhead
vanguard; advance guard
original inhabitant; aboriginal
deciding first; settling (a matter) first; first priority
tip of nose
earning the first (runs); preoccupation
storefront; shopfront
recipient; addressee
sending ahead
tip of the hand; (use of) one's hands
the other day; some time ago; recently
edge of the eaves; house frontage
edge of blade
recently; the other day
pen nibs
preferential
previously; before; earlier; formerly; recently
lower future quotations
prior to; before; in advance of
some time ago; the other day
developed country; advanced country
customer; client; client company; business connection; trade partner
(regular) customer; client; patron; clientele
contact information (address, phone number, etc.)
delivery address; address for delivery