Suffix used in compound words to indicate a route or road, such as in 街道 (highway) or 通路 (passage). Not used as a standalone noun.
The 路 in 街道 is a suffix meaning a route or road.
distance travelled in a day
Rare suffix indicating a day's travel distance, found in classical or historical contexts. Not productive in modern Japanese.
one's ... (age, e.g. 40s, 60s)
Suffix attached to numbers to indicate a decade of age, as in 四十路 (one's forties) or 七十路 (one's seventies). Somewhat literary or old-fashioned; 代 (だい) is more common in modern speech.
See also: 七十路
In classical texts, 路 was used as in 一日路 to indicate a day's journey.
He has just entered his forties.
代 is the everyday suffix for a decade of age (40代), while 路 (as in 四十路) is a more literary, old-fashioned alternative.
路（ち／ぢ）is an archaic word or place-name suffix meaning 'road', whereas 路（じ）is a separate, still-used reading meaning 'route' or 'journey'.
age thirty; one's thirties
lane; alley
journey; route of a journey
the road home; one's way home
age fifty; one's fifties
mountain path; mountain road
age forty; one's forties
romance; love's pathway
dreamland; realm of dreams
The kanji 路 originally means 'road' or 'path'. Its use as a suffix for age decades may derive from the idea of a 'path' through life. The reading じ is the on'yomi.
sea route
river's course; river path
main street; main thoroughfare · most important of the three classes of highway (ritsuryō period)
deva realm; svarga · path in the heavens; sky path
coastal road; seaside road
tideway; sea route
field of vision; range of vision; line of sight
sand path; sand road
sea route; voyage
path in a field; country path
dark road
day's journey; one day's travel