means Stretching out a hand, an argument, or an ambition toward something just beyond easy grasp — often used dismissively when someone strains too hard to make a connection that isn't really there.

from From Old English 'rǣcan,' meaning to stretch out, hold forth, or extend the hand — a cousin of Dutch 'reiken' and German 'reichen.' The literal sense of physically extending an arm came first; the figurative senses (reaching a conclusion, reaching out emotionally) grew from that same image of a body straining toward what lies ahead. The modern slang meaning — 'you're reaching,' said when an interpretation overstretches the evidence — is a natural extension of the same gesture: a hand grasping at air.