He is thoroughly familiar with the mountain paths around here.
Tips
memory
Radical is 禾 (grain) — the original sense is 'grain ripening,' which extended metaphorically to 'long acquaintance ripening into familiarity' (稔熟 rěnshú = well-acquainted).
register
Almost exclusively literary or in fixed compounds: 丰稔 (bountiful harvest), 稔知 (to know well), 稔熟 (intimately familiar). Not used as a free word in modern speech.
