flute, clarinet, pipe, whistle, bagpipe, piccolo
笛 centers on wind instruments that produce sound through a hollow tube: flutes, pipes, and whistles. The specific instrument names (clarinet, bagpipe, piccolo) are natural extensions of this core idea of a blown musical pipe.
笛 combines 竹 (bamboo) with 由, which likely contributes a phonetic element. The character originally referred to a bamboo flute, and the bamboo component reflects the traditional material.
The top part 竹 is bamboo, and the bottom 由 looks like a field with a path through it. Imagine a bamboo flute carved so that air flows through it like a path through a field, producing a clear note.
For テキ, imagine a technician (テキ) tuning a bamboo flute: tech -> テキ, and the technician's precise adjustments make the flute sound perfect.
flute; fife; pipe; recorder; flageolet; shakuhachi; clarinet
whistle (sound made with the lips)
flute player; flutist; flautist; piper
steam whistle
horn; alarm; whistle; foghorn
horn (instrument; made of animal horn); bugle; hunting horn
Japanese transverse bamboo flute (high-pitched; usu. with seven holes)
transverse flute (e.g. a fife)
reed pipe
drum and fife band
the Pied Piper of Hamelin
to whistle
siren; whistle
windpipe
bluestripe snapper (Lutjanus kasmira); bluestripe seaperch
kagura flute (six-holed horizontal flute)
whistling through one's fingers; whistle made by sticking one's fingers in one's mouth and blowing
spotstripe snapper (species of fish, Lutjanus ophuysenii)
spangled emperor (species of emperor bream, Lethrinus nebulosus)
Papuan black snapper (Lutjanus goldiei)